Pro's and Cons'
350Z IMO looks way better, its RWD (not sure if you like that option) It's a big chick magnet (not sure if you like that either hopefully you do), It's got a bigger price tag of course...
RSX Will most likely be faster, probably a better chance of getting stolen (thanks to the new motor mounts coming out to fit civics and stuff) umm can't really think of anything else, I personally would choose a 350, but thats my opinion research them both and make a decision based on what you like more.