I have voted pop... but then I also like The Beatles and The Who and other 60s bands and I would consider them to be pop rather than rock in most instances so it's hard to actually vote. My taste falls somewhere between pop and rock.
My favourite music era is the early 80s stuff by bands like Human League and Duran Duran which would fall into the pop category, but my favourite band is Muse which is classed as rock.
Yep, I'm not always sure whether to denote something as pop or rock. I tend to think of pop as something that is played frequently on mainstream radio, and doesn't easily slot into a more specific category. So, off the top of my head...James Taylor is someone I would consider as a great popular artist. His music can appeal to a lot of different folks, and you can easily hear his songs everywhere, from restaurants to doctor's offices.
One of my other favorites is Joni Mitchell, but she never had the mainstream appeal of James Taylor, and probably would fit somewhat into the folk category.
The Beatles had mainstream popularity, but I guess my mind wants to put them in the Classic Rock category. Maybe that's just how much I like their music, that I feel the need to put them in my favorite category.