I'm playing World of Warcraft again. I've played it since I turned 14 years old. It was in the september of the last year of vanilla WoW. I've made quite some breaks in the mean time, some lasting for aprox. 8 months, but I've always been a WoW player.
I have tried many other MMO's like Tera, Runes of Magic, (...), but they always felt very weak in comparison to WoW.