Back in the days when my latest album was Busted's "Busted" (2002 album), so...about 2007 ;P I used Windows Media Player...because I didn't have a PC, I just used my dad's, and he was really strict, so all I did on it was play Tribal Wars.
However, we got a laptop, and my brother got an iPod, so we got iTunes. I found that to be brilliant (Even if he did refuse to let me put my music on it). Since then, I've kinda used iTunes whenever I used anything (At one point all my music was on my phone). Now I've got a separate account on the laptop, and literally all I use is iTunes. It's just what I've gotten used to, and seeing as I hope to one day get an iPod, I doubt that's going to change. I also find it fairly easy to use (Although sometimes it has to be aggressively negotiated with in order to get it to choose the right album artwork. Or accept that aforementioned artwork exists).