Historical study, today, tends to be fairly specific in academic focus in that most historians very clearly target their work within one, or a couple, areas of history. For example, this may be 'social', 'economic', 'political' - I'll get more into these in a sec. It's rarer now to see academic works that aim to provide comprehensive and one off works that answer every question and cover every theme on one historical area. Therefore, the field is really quite hard to summarise right now as it's so complex, varied, and continually developing. Also, there is quite a strong divide right now between academic history and 'popular' history - the 'ivory tower' complex is fairly strong with many historians writing pretty much solely for academic circles. Of course, this isn't always the case, but the discipline is fairly out of view right now in the West, partly thanks to the sharpening of "culture wars" recently that has caused much history to be grossly simplified and shaped through modern political aims - this isn't unique to the present day, but it is quite acute right now, thus limiting public access to much historical study.
Regardless, within the academic field of history there are still some broad themes present, many of which have been explicitly labelled and examined by historians in their own right.
If we start from the 1800s, which was roughly when history as an academic subject as we understand it today was increasing in study, we see that, as you mentioned, Great Man history was most popular. Personal studies that claimed to examine whole eras were popular. These weren't without value, but often simplified history to a point that we tend to reject many of their conclusions today.
Throughout the early 1900s, some Marxist history was becoming popular, but overall work was still fairly "broad" with many still taking a personal approach. I'm not super familiar with this era in terms of academic history, however, so may have missed something.
It was in the 60s that Marxist 'material/economic' history really took off. This was then supplemented in the 70s with the development of feminist, racial, and culture based studies - the foundations of 'social history. This culminated with the 'cultural turn' in historical study that took place in the 80s and 90s. This was when historians really began to try and look at societies, or parts of them, rather than individuals. Greater emphasis on "little people" emerged and greater cross over between social sciences emerged. It's also interesting, because it was in the 1990s that the fairly brief "end of history" movement took place following the fall of the USSR - this was the Western belief that the whole world would eventually fall into copying, to some extent, American idealised capitalist democracy. This was shattered pretty forcefully with 9/11. The 90s also saw serious analysis and criticism of the Western scholars having employed 'orientalism' in their studies of the colonised world in the past - search up Edward Said for this.
It was after 9/11 that we begin to enter slightly more confusing times in drawing out trends in studying as we become close to the present day. The 2000s saw a lot of work on the USSR as archives were released, with many, ironically, "socialising" Soviet history as the 'lower level' sources finally became available. However, the 2000s also saw a lot of slightly frenetic considerations of Western history thanks to the confusion following the challenge to the Western confidence of the 90s that Iraq, Afghanistan, and increasingly China presented.
This brings us up to the 2010s through to today. There is now a very strong emphasis within history on trying to create "interdisciplinary" and "intersectional" history. These are, to some extent, buzzwords, but they are genuinely very important buzzwords as they summarise the basic attempt of trying to both limit and broaden historical studies based on recognising the nuances and limits of investigating the past. There is a greater acceptance of how there isn't really one "true" history that we will ever discover, but rather simply the images that we can create based on our sources, analysis, and own interpretations/influences. I'll list now some of the more dominant approaches.
New Political - an attempt to combine the details of individuals, institutions, and broad social studies.
Economic - material, often statistically focused, lots on trade as shaping history
Social - as explored earlier, broad category that a lot of sub focuses could focus on. Often not about creating a narrative or explaining an event, but rather trying to understand "what life was like" for different parts of the population.
Gender and Sexuality - a focus on re-interpreting historical events throug these lenses. Often, this label gets talked down a lot, but it actually contains really interesting nuance and variety within it that is well worth engaging with!
Race - similar to the above, but with race. Very interesting discussions on what race has actually meant as a concept throughout time and how these conceptions have shaped societies. It's not just "discovering" (if you're patronising) or "inserting" non-white people - though some popular history does focus on this element.
Culture - lots of buzzwords in this one, but interesting considerations of how societies develop, often using less utilised sources such as objects, images, music, traditions etc. 'Invented traditions' by Eric Hobsbawm was a Marxist approach that helped launch this kind of study.
Decolonising/Against Euro-centrism - a very broad label that works to turn Western academic history away from stereotypes and broad proclamations about the world and towards studying the interconnectivity of society in a nuanced and detailed manner.
These are all simplifications and summaries, so feel free to research them yourself! Oh, and all from a Western POV! The long and short of it is that the subject of history is as complex as history itself - infinite. You can class your approach in a thousand different ways and labels - sometimes this is really helpful as it focuses and unites studies, sometimes it leads to pedantic semantics. As with all historical study, it's your job to evaluate what you see and interpret things as you believe is most strongly evidenced and argued. Whilst history currently is swamped in 'isms' and other complexities that may make it seem frustrating, there is so much interesting research going on right now and a lot of the terms are actually very simple once broken down.
Like all academics and sectors, history has wrapped itself in terminology, but at the end of the day history is uniquely universal, so look at it however interests you the most, and as always, be aware that you'll never know it all, nor will you ever know the "truth."
On this particular question — is it "great forces/conditions" or "great men" — my sense is that pretty much all historians would agree that the forces/conditions that deserve much of our attention, but that this does not necessarily preclude human agency. That's the bind: how can we be both at the mercy of forces, and yet actually feel like choices are made? There's a paradox here: modern historians believe two seemingly contradictory things as a matter of faith. One is that the conditions and context of the past matter for determining how it proceeds (you could call this historicism). The other is that much of the past was largely _contingent — it could have gone other ways. Historicism is what drives the overall worldview of a modern historian; it's why you do this, because you think that the study of the past will actually give you some insights into how the world worked and maybe works. Contingency is baked into almost every description that historians write; if not overtly, look for anytime they say something was "important" — that is code for, "I think if that thing hadn't happened this way, the future would be really different."
And the resolution to this (because it is not really a paradox) is that in any real-world situation it's always going to be a dynamic feedback loop of sorts between your human agency and your structural forces. The preexisting conditions shape the possibilities and the status quo. The people within those conditions, though, do make choices, and some of those people have more influence over other people than others ("power"). So the choices of some people are going to have a pretty big impact on whatever goes into those forces/conditions, but they aren't absolutist about it (even in absolutist societies; they can't control the weather, for example, and they can't, as much as they'd want to, have total control on public opinion). And all of those sorts of "human things" feed back into the forces/conditions again. And so on and so on, forever and ever. That's your synthesis: it's a big mess and there isn't some easy "rule" about which one matters, except that the idea that it's all human agency is totally on the rubbish pile, and for I think most historians, the idea that it is 100% materialistic (all forces, no agency) is also not very useful (certainly it is not how they write history).
The big difference between your average modern historian and your Marxist historian of yore is that your average modern historian admits more forces/conditions than your stereotypical Marxist. It's not just class struggle. It's the environment, it's technology, it's ideology, it's gender, it's race, it's interactions with other peoples, it's "culture" (which can mean pretty much whatever you want in terms of human agency), it's anything and everything under the Sun. This is the part that doesn't feel like any kind of "theory" so much as a framework in which your theories can go; it's where all of these sub-fields of analysis come in, because various historians prefer to focus on one or two of these things (because trying to account for all of them at once leads to total scattershot incoherency).
This kind of stuff isn't really the "theory" that historians care about today, though. We're not having debates over this sort of thing, except when (every once in awhile) some non-historian gets famous with an overly simplified theory ("Great Man was great, actually!" "It's all about environmental determinism!" "It's all about One Weird Trick that Historians Hate!"), at which point the historians raise their gaze away from what they'd normally be doing and explain why these kind of mono-causal frameworks are, in fact, not that useful and leave out a lot of important stuff. Then they go back to whatever frameworks they prefer, which are less of a "this is the secret to understanding history" sort of thing, and more of a "here's a way to look at history that reveals patterns and trends that we've previously overlooked" sort of thing. Because in the end, that's the real change, not so much historians' stance on this "debate," but whether this kind of debate is asking the right questions at all. We're not searching for a new "theory" of history; that approach is dead as a doornail. We're looking for new questions to ask of the past, because that's the only way to get really new and interesting answers most of the time. The Great Man/Forces debate is a false dichotomy, and a mostly boring one, as well — at least to modern historians.