The majority of 3D games lack a sense of artistic direction. In this sense I prefer 2D games. That being said, most 2D games are Japanese and are stuck in the, often stagnant, conventions of that industry. One drawing of girl, that drawing with panties erased, that drawing with dick drawn in, that same drawing with dick barely inserted, once again the same drawing with cum effects. All the while the text is insisting that he's definitely balls deep and loads of things are happening just trust us. Drawing is hard, so many 2d games lack any sense of dynamism in their sex scenes because they are trying to get by with as few drawings as possible. Western 2d games generally get around this by drawing more, less detailed, images per scene. I generally prefer that approach, though it has its obvious shortcomings.
3D has a definite advantage in dynamism, as you can just make them move for real, but this ease can result in a somewhat thoughtless product. There's a lot you can get away with not considering in 3D, that really would benefit the game if a dev stopped and considered it. A 2D game that considers pacing and imparts a sense of movement in its scenes, or a 3D game that does not lean on the technology as a replacement for artistic talent/intent will be fairly evenly matched in my book.
I'm good with either, honestly. I have a slight preference for 3D most of the time, with the one caveat that if it's a work using characters from an anime, whether fan fiction or parodied, anime-style 2D (i.e. Koikatu, etc) seems like the better fit to me. I've seen some flat-out amazing renditions of characters from anime I watch or have watched (notably the entire Macross franchise, as well as To Love-RU), though sadly I can't remember off the top of my head who created the really really good ones.
Depends on the rendering software, from what i've seen. if we're assuming Koikatu for the 2D stuff, then if we stick with Illusion for the 3D as well (Honey Select, HS2, AI Shoujo, etc) then there's no real difference in rendering difficulty -- jsut a matter of the dev's preference. On the other hand, if we still use Koi for 2D but switch to DAZ or Blender for the more realistic 3D, then yeah 2D is way easier, because DAZ and Blender are far more complex, and DAZ at least can take hours to render a single frame. Potato/potahto, more or less
I like both, I think the answer comes down to games that have better art/assets. Like a game like My Pig Princess is gonna capture me with that sweet art but at the same time Hooked! is amazing too. I wouldn't say one is better over the other just cause 3D or 2D. Comes down to how much effort and skill is put into the look for me.
From what little experience I have it's much harder to make a 3D asset than to make a 2D asset, so in an "industry" like the h-game industry where it's usually a solo developer 2D generally ends up being higher quality. There are exceptions of course but from my experience 2D is generally higher quality. Assuming it's not an rpg maker game. with default assets everywhere.
2D games are scarce and often get abandoned because it was just the artist's side project. 3D games get abandoned too but at least they put out a lot more content before that happens.
99% of completed 2D games are Japanese and I've gotten sick of them. There are some great western 2D games, but it's like one per year, and sometimes not even that.