Don't get me wrong, I like achievements and trophies, but I would never use that for a basis in terms of what platform to buy the game for.
Which is odd, because I prefer good single player games over multiplayer games any day, and the achievements and trophies are geared towards single player (except Halo 3 maybe?). If I'm playing a game that has it, I'll try to unlock them..but if it doesn't, I don't even think about it.