I like seeing how the various members' tastes in music overlap. And the diverse tastes as well!
When we used to choose cover songs, I had what turned out to be a pretty good idea that kept everyone happy. It evolved from when friends would come over and want me to put on some music. I'd say, "You pick something, because if it's here, I already like it, but if I choose, it might be something you don't care for."
I basically said, we wouldn't even be in a band together if we didn't have common tastes in music. So, imagine we each have a circle with all the songs we'd want to do in it. Where those circles overlap, is where we pick songs from. It worked pretty well, and we actually discovered some things about each others' musical tastes we hadn't known.