The first non-children's album I got - back when I was about 12 - was Air Supply's Greatest Hits

I used to listen to adult soft rock stations and hated the pop/top 40/rock stations. As I went through HS, I started listening to Billy Joel, Elton John, Madonna, Erasure, Bon Jovi, maybe a little hair band music like Motley Crue and Poison. Just p!ss-poor musical tastes at the time.
Fortunately, going to college changed things a bit and I started listening to The Cure, NIN, Depeche Mode, New Order. But perhaps what broke down the walls for me was discovering progressive/psychedelic rock...Pink Floyd, King Crimson, Yes, Genesis, ELP, The Velvet Underground, Gentle Giant, Van der Graaf Generator, Eloy. Finally my mind was freed from liking only simple song structures and I developed a tolerance or even a liking for odd time signatures, complex arrangements, atonality, etc. And I also discovered that the most glorious of all electrified musical instruments is not the guitar but the Mellotron!
Now my tastes are pretty broad within the rock realm. I have Moody Blues CDs next to my Metallica CDs and Smiths albums next to my Sonic Youth albums. My favorite album is perhaps unclassifiable because there is no genre that suits it: _Spirit of Eden_ by Talk Talk, the '80s new-wave gone post-rock band.