What do you like more on mobile, pops or banners?
and why?
Display 3 - 2 Pops
Don't forget to say why you like your choice more 
I have not tried display enough yet. BUT if I can make display work, as well as pops, then display is way better because it has more volume potential and less competition (probably less than pops), so DISPLAY! 
It depends, in the follow along section people are banking right now on both. The thing I hate about pops is the click loss, especially since I would have had profitable campaigns if I could eliminate it but what I do like is not having to worry about banner performance and that traffic is cheaper.
As for user experience, personally I don't mind if the popup is something that catches my interest and not an adult landing page from a cloaked affiliate whilst I'm reading song lyrics on a train... never closed a tab more quickly, so glad nobody saw that.
I prefer pops at the moment. I began with display and didn't have much success. Maybe I'm just impatient and like the bigger amounts of traffic/faster data with pops. I haven't given up on display though as I know the potential is there.