If I had a 360, I'd be able to compare them, but overall I do prefer the trophies over achievments after experimenting with Achievments with my friends Xbox. There's something about actually having a Trophy over a puny little number. We all know that Silver beats Bronze and Gold beats Silver it and Platinum beats Gold and those add to your "Trophy Level" in a percentage, but with the numbers it just seems as if "20, 50, 100!" to add to a arbitrary number that do nothing. That's not to say I don't like achivements, I beg my friend to let me actually beat the first level in Halo 3 (he only plays multiplayer), I just prefer the shininess of trophies than the numeric value of achievments.
Of course, that's my humble opinion, but trophies do make me go back and explore a bit more. For example, I'm playing Burnout: Paradise now in hopes to get the Burnout License, and it's great fun doing so. Other trophies like "kill 5 enemies with one punch after softening them up with gunfire" in Uncharted just make me yell "No way, fuck you!" (I could never get that one, I end up killing them with more than one hit...)