I use both loops and sequenced rhythmic patterns... Loops can be really useful - I tend to make my own ones when I'm not in the mood for making real music, save them as .wav's and use them later. And loops aren't just meant to be stuck behind the rest of the beat, you can chop them up, layer them, use FX on them... a whole world of possibilities! :) Plus they can work really well with your own drum patterns, as it was pointed out in one of the above posts... That said, I'm against sampling someone else's loop and just sticking it in your tune, 'cos that's just plain non-creative, and you might get sued if you release it anyway :)