I think bangin beats can either be made by sampling or composition. I like both. Like def said, i like that kind of sampling where the sample is chopped up so much that it's basically a different song. It's always amazing when you hear the original and your're like, how did they do that? One of my favorite things to hear is sampling and composition combined. If you know what you're doing, that is a dangerous combination. You'll nod so hard your head will fall off!!
I have yet to find a set of keyboard sounds that I have been highly impressed with. With that said I prefer sampled beats. I prefer to sample myself for that reason. I have made composed beats but I am never satisfied wtih the sounds used.