What areas of history have the most and most active topic experts? Which areas attract a lot of rubbish and few good responses?
Military history seems to be a strength, which isn't surprising, and there are some very good medieval historians. On the other hand, economic history does not seem very well represented (this would be my own specialism if I'd worked harder at university).
We are absolutely outstanding at British naval history :-)
No, kidding aside, I think that our flairs seem to be well versed in their individual specialties (the review process is very solid), so a partial answer to your question might be found by looking at our list of flaired users: http://www.reddit.com/r/AskHistorians/wiki/flairedusers
European history is clearly the best represented in that list, but there are strong contributors in many fields.
A better way to get at your question might be to take a look at the types of questions we get, which you can approximate by looking at our FAQs:
http://www.reddit.com/r/AskHistorians/wiki/faq
You'll see that there are some major areas represented there that are kind of what you'd expect: what did people do in the middle ages, how did technology get lost or change over time, what's up with the atomic bombs, boy that Hitler guy huh?, and lots of questions about areas that are vaguely understood by the questioners (pre-Columbian America, for example).
One thing to keep in mind is that other than the daily rotating threads, this sub is essentially a responsive discourse -- people answer questions that others ask, and so the type of things we talk about are somewhat constrained by the questions that are asked. I wouldn't be surprised if you thought up and asked a good question on economic history to see some possibly less-frequent contributors pop in with good answers.
I don't think we're great at prehistory, unfortunately. There aren't very many of us with flairs in it, and if we don't get to a thread first it tends to very rapidly fill up with howlers. Lot's of people seem to think (and, astoundingly, explicit say!) that because prehistory comes with comparatively few "solid facts", there's a license to speculate and/or make vague generalisations based on knowledge from unrelated fields. For my own part, by the time I've done cleaning up and rebutting things in threads like that, I don't usually have much energy left to write a proper answer myself. But maybe that's just because it's my own field and I notice it more.
More objectively, we've been aware for a long time that our flaired userbase is massively skewed towards modern European and American history, while African, Asian and South American history is under-represented. What to do about it has proved a bit of a head-scratcher though.
As /u/jschooltiger pointed out though at least some of this is to do with what people ask about rather than what we're good at answering. We're frequently contacted by people with really cool, niche specialisms who are frustrated because they never get the chance to share their knowledge.
I generally like this sub but I'm going to strongly agree with you that this sub is noticeably wanting in economic history, particularly of a more technical variety. I've asked questions before about things like the flow of silver specie in the 16th century, the consumer goods sector of the USSR, the causes and effects of Japanese conglomerate business, commercial revolutions in 17th century England, the structure of early industrial r&d, and so on, and I've either 1.) received no answer or 2.) received terrible answers. I don't think I've ever received a half decent answer on an economic history question I've asked. Again, this is a good sub, and I've gotten some great answers on other questions, but this, imo, is a glaring hole.
As has already been said the deficiencies that appear in answers really more reflect a lack of questions in a particular field. For example there are almost no questions on Historiography and Historical methodology, that does not mean there are not people capable of answering these questions only that the questions are not asked.
The slant towards European, North American and Military History is pretty easy to explain considering that the userbase of askhistorians is mostly European, American and interested in Military History. There's nothing wrong with that, I myself am British and, obviously, interested in Military History but I wouldn't see it as a sign that askhistorians is 'bad' at other fields.
The sub surveys have shown that women are underrepresented among the Flaired, and I don't see a lot of activity in the realm of women's history. To be fair, there don't seem to be a lot of questions about women either. I suppose this is to be expected since there aren't any women on the internet.
It's a common complaint that we don't have enough users versed in Indian history. I'm aware that at least one of the moderators here has wanted to do an AMA on India for ages, but there are huge gaps and we don't have enough people. This is pretty sad, because that's a huge gap in history that most users here don't actually cover.
Also, I wish we had more questions about women, because there's this misconception that women don't have a history to talk about (or that their history is limited to the walls of a house), and that isn't true.
Also, a less Eurocentric look at history would be great, although this is a wider issue that extends outside AskHistorians.
I've noticed this subreddit tends to be really good at history of the world's "events" (especially military and political history) and the history of science, but it's fairly weak on history of art, fashion, literature, and especially weak on the history of music (with some exceptions, of course). I come across a lot of threads that touch on history of the arts, and I often see thin or outright wrong comments at the top, or the threads unanswered and downvoted. :-(
The subreddit could do with one or two expert ethnomusicologists, for sure.
Otherwise, I'd say the main thing this subreddit is especially good at is sussing out b.s., and calling people out for uninformed or unhelpful answers (and questions).
I'm surprised we don't have a Maya expert among the Meso people. I mean, we have Tarascan and Teuchitlan people which is hardly a talked about subject. Maya researchers seem to be a dime a dozen to me.
Although most of us involved in Meso have studied the Maya and we all contribute and answer any questions that pop up.