Well, to address at least part of your question, as it specifically pertains to China, it's important to talk about the actual term in a historical sense in China as well as what the denotation of the word "peasant" is that we're using.

The historical Chinese peasantry themselves are referred to as "Nong Min"/"Nong Class" (农民／農民) and it comes as part of the four occupations which is something that has very very early, pre-imperial China, roots. As a warning, I'm going to be interchangeably using the terms Nong and peasants/peasantry, and unless otherwise specified, these will both refer to the same thing: the occupational class within China. The peasantry would've been the largest class of society, and while their social status/position and the regional economic, philosophical, and political climates may have been in flux throughout the span of what we can consider "Chinese" history, the term used to describe the peasant occupation doesn't change. Nong are still Nong. This is true for the Shi (士) aristocratic class as well; i.e. they weren't commonly going about commanding battles from chariots and didn't have the same sort of duties during the late imperial years that they would have during the pre warring states years, but their occupation/class name remains the same.

But, back to the peasantry. So as I said, their actual production methods and place on the social ladder shifts around quite significantly throughout how many odd years you'd like to define as encompassing "Chinese" history. In the pre warring states, pre-imperial times, they participated in what can be likened to a more feudal arrangement with the very famous "well-field" system (JingTianZhiDu 井田制度) where large plots of land were divided into a "well" shape (as in, like the character jing 井) and arranged as so. The outside allotments were tended individually by peasant families and their production was used towards their own needs, but the center allotment was tended by all the families and strictly for the Shi who presided over the land (and this would then be leveraged within the "feudal" arrangements present in China at the time, or used for some other purpose). Later, you get stuff like the equal fields system under the imperial government which cycles set plots of land to a set family, and then they either pay their tax through grain produced or later through silver earned from selling the grain.

Where does that leave the Nong in the social order though? Typically in the western world, we view peasants as being the lowest on the social scale. We can roughly form a pecking order of: Kings, Lords, Nobles, Functionaries, Warriors, Merchants, Artisans, ... Peasants (or whatever terms you'd like to use, swapping things up as necessary. It's a vast oversimplification of things, but let's just take it as a comparison to say that peasants are typically not put anywhere but the bottom). In China though, the peasantry isn't as low as one might assume. Certainly, they're not on the same level as the Shi aristocrats, but it surprises many to learn that they're not dead last. In fact, they're quite high. The Nong were viewed as a more noble occupation than the merchant class or even the artisan class for a good long time within Chinese history. That seems crazy, and let's not delude anybody into thinking that being a Nong granted you nice privileges or prestige, but the core idea is that they were producing something for use (grain, silk, etc. food and clothing materials are pretty useful things) whereas the merchants produced nothing whatsoever, merely sold others works for personal profit, and the artisans were lumped into the same category, producing goods that were not communal goods or goods to be consumed rather, producing goods to be sold for a profit as well. Over time though, these classes evolve. The artisans become a far greater economic force by the time of the Song than they were in the Han for instance, with ceramic production at Jingdezhen booming, and by the time of the Ming, there are even wage-labor systems in place for the artisans. The same is true for the merchants: during the Song, they leverage economic power into social power, and in the Ming and on grow to be the drivers of the Chinese economy, rather than the state monopolies that had been the fashion of the early imperial dynasties.

What does this even have to do with your question? As you might have guessed by now, I'm pretty much in the camp of using the term "peasant" for the nong class, but it's necessary to have all this kind of background information and to know more about the class specifically as it pertains to China before coming to that conclusion. We could call them nong, but also as I just played out, a nong of the Zhou is a different situation and representation than a nong in the Tang, and it makes it even more complicated that the term is still in use today. It's something you see quite a bit in Maoist stuff, these linkages between the historical peasantry and the farmers of the time with the term Nong Min. Notice here for example. These people are not just the general "farmers" (which would be nong fu 农夫/農夫), the term used is nong min (農民 in this case), the historical occupational term.

I personally use it as a general term to describe any non-aristocratic pre-industrial agricultural worker or smallholder. As needed, it can be broken down into more specific and useful subcomponents, but it's a useful shorthand when speaking broadly.

I think the problem of the definition of peasants is actually very similar to the problems of the definition of slavery. How are we to quantify a grouping of people that has separate legal, economic, and cultural connotations across regions?

As usual, I think Chris Wickham provides a useful definition that I've been more than ready to apply to China as well, simply because it attempts to separate the legal from the economic, and setting aside the cultural.

Namely, a peasant is a settled subsistence agriculturalist that has to spend some of his time working in the field cultivating his own produce (p.386 of Framing, if you're interested). As soon as the agriculturalist is able to avoid any such labor, he is no longer a peasant, he is a "medium landowner."

This of course, jives with marxian notions about what is capital and what is labor, namely you obviously can't live off the "interest" of your own labor (it always has to be worked by you), whereas you can with capital. And of course, it has applicability to even our modern era, for example with the politics of American farming subsidies ("should we be subsidizing agricorps who are agriculturalists but not the type we think of when we think of small-scale farmers?").

I think the idea is that from this economic definition, perhaps we can draw a line as to the common majority of agriculturalists throughout the pre-modern world. Whereas if we're dependent upon the individual legal and cultural definitions of each society, we will fall into an eternal nominalism.

So, I use peasant but in a different way than what you're probably thinking. I use it as a translation of the Rabbinic Hebrew term am ha-'aretz, which literally means "nation of the land", which is a common label in Rabbinic texts from the Tannaitic (pre-compilation of Mishnah) and Amoraic (pre-compilation of Talmud) period. It's a term that is difficult to translate. Sometimes it just refers to Jews who are not particularly versed in Jewish observance (so their performance of rituals cannot be relied on). Sometimes it is used to refer contemptuously to the ignorant, in a more extreme version. Sometimes it just seems to refer to people who are jerks in general.

Anyway, what make this suited for "peasant"? Well, the am ha-'aretz are associated with agriculture. They seem to be the rural people who don't really care what the Rabbis are proclaiming these days, which is why the Rabbinic authorities really don't like them. So when the term is used it definitely has some negative connotations, which are more tied in with general backwards-ness than with anything else. The opposite of them is the haver, or "peer", marking the am ha-'aretz as the outsiders, the opposite of the Rabbinic establishment in Jewish life.

The nice thing about the term "peasant" for this purpose is that it does have negative connotations. The term evokes images of medieval dirt farmers (probably dirty, illiterate, and provincial) rather than a more positive image of a subsistence farmer (the fact that I can't make up an example on the fly says a lot, actually). And that's exactly what's meant here. The term is supposed to be somewhat derogatory, it's supposed to talk about a state of life which is not appreciated by the writers and readers. No other term will quite do for the term.

Anyway, over time the concept of the am ha-'aretz faded, as Jewish subsistence farming stopped being a thing. They were replaced in discussions by the more neutral hedyot, who is simply a normal Jewish person without any specialized knowledge, without any particular connotations about their way of life in general (the best translation is probably "layman", though as a bit of trivia it is etymologically related to "idiot"). But, it's still handy to have a way to refer to them. And for this the fact that "peasant" has negative connotations is actually helpful.

I should note that I didn't invent this or anything. There are a couple translations that translate the term that way, and I started thinking about this a bit more from this discussion from /u/yodatsracist.

tl;dr I use it for the translation of an ancient bit of terminology, for which its vagueness and negative connotations are actually helpful