2D allows for greater variety of art style.
I would have a higher opinion of 3D if more people experimented with art style and didn't use all the same assets.
Depends on the game, I love a good 2d rpg game and 3d renpy/unity games are great too, but when ever I see a new game using the default characters in DAZ or koikatsu party, that is an automatic skip.
If you asked me a few years ago, it would be 2d no doubt. However, 3d games have been getting better and better, while good 2d games aren't as common I feel.
I think in general now though, 3d games have the better sex scenes when done right. While 2d games are likely to be more fun in a gameplay sense.
To me it doesn't matter so much whether the game is 2D or 3D, so long as the game is well designed, engaging, with good quality artwork, and interests me.
Games tend to look better in 2D when they're made by inexperience devs, since designs can be hand-drawn. 3D can easily look terrible with poor animation and lighting.