I think it depends on a lot of things. What type of game you're making, target audience, is there any mechanic that requires 3D etc etc...
that is clear, but maybe I explained the question badly..
in a game with the same feasibility, having to choose between one and the other, what graphic style would you choose, and why? pros and cons?
I'm not speak just about aesthetics, but also, for example, the difficulty of animating a mesh rather than a sprite, etc