It mostly depends on your preference. All of the clubs i've been to have a couple turntables, as well as cd players, and whatever else the DJ brings with him. One of my friends spins mostly records, but also has a cd player that he busts out sometimes. Some things you can't get on vinyl i guess.
the mp3 cd players are really cool though, I mean you can spin 2 cd's all night if you wanted to.
Personally, i'm looking to buy some equipment soon. I'll probably start with a couple of turntables, but make sure i have extra inputs on the mixer so i can hook up a cd player in the future.