Anything that gives me "that feeling", that evokes emotion.
Of course i love those intros or instrument breaks with no drums, it makes chopping easier. but if it has drums, I'll try to make it work if i really like the sample.
For me, im usually level 2. I'm chopping stuff, but am not too concerned if its unrecognizeable. i think the way i chop it is most important. making it sound ill.
if im straight looping it, then its gotta be rare, or something taken out of its original context.
sometimes ill find 1 note on an entire song that i like, and cant really do nothing with it, but that 1 note sounds so nice. usually ill just save it for later or get lucky with other sound im currently working with and end up making a beat.
peace