I like music that was considered mainstream 30-40 years ago
Led Zep, AC/DC, The Who, The Rolling Stones, Pink Floyd, Jimi Hendrix, Journey, Queen etc etc
As for now the only mainstream band I like are The Red Hot Chili Peppers and before that (10 years ago) Blink 182. It's not like I hate on things because they are popular, it's just that most of the popular bands around now that I've heard do nothing for me musically. I'm sure there's plenty of popular stuff I haven't heard that I'd like though and of course there will be stuff in the future I'll like that's popular. Nowadays I mainly listen to Metal (mainly Melodic Death/Black metal, Progressive Metal, Tech Death Metal, 80's style heavy metal/power metal and Thrash/Groove Metal), some electronic music (trance, house, some dubstep)and classic rock of the aforementioned bands (among others).