Both. I started off as an Ally Play: 85 warrior(The original Sprixx!), Warlock(My first 60 in Vanilla), and Shammy(RESTO BABY... and now Horde)
Then my friend re invited me to play again start of the year, and I leveled a Protidin, and Huntard to 85, and a 81 Priest. Now my Shaman is Hordy too. MY warrior and Lock are still my favorites, if not my mains anymore. I also have a Worgen Drood at like 70 something. I've played every healer and tank out there too at least 70 (DK too but not much). My pally was only Holy briefly but it wasn't really my thing. All my main specs is either healing or tank (Drood was both xD) because I love being the thing that keeps everyone alive, THE PRESSURE! I LOVE IT! (I am insane!)