Vanilla: Was in one of the Top rated raiding/pvp guilds in the EU. Blizz live streamed our AQ40 run at blizzcon and The gathering norway. At the time we were one of 4 guilds who had cleared the entire dungeon including optional bosses, Our Twins tanking warlock Dc'd during a vital phase in front of all the viewers. I was playing a shaman at the time and somehow ended up with the agro! popping pots and getting quick rebuffs from a priest I managed to tank the twin until our warlock came back online.
The next day Eye of sulfuras dropped from a rag run, everyone in the guild new that Hand of Rag was a pure pvp weapon so for my saving of the twins I was awarded it.
By that time I'd amassed a lot of very good high tier melee gear and proceeded to open a can of **** on the poor alliance unlucky enough to meet that weapon. That was it I was hooked on pvp and went to R13 in the ranking system at the time

That sparked my taste into pvp and I ended up with multiple level 60's by the time TBC came out all with R11-12
The Burning crusade:
Tanking as a druid in sunwell was fun as hell
World pvp at Halaa
Ganking the elemental mote spawns
Sadly TBC for me wasn't the best expansion I loved the raiding and pvp but they destroyed the joy of melee shamans (Okay so it was a bit OP with 2h but they only had that and RNG to go on really)
Wrath: didn't play
Cata:
Dual wielding 2 massive weapons on a warrior and doing respectable in pvp with it, destroying bosses with unlimited DPS and downing the first heroic worm boss
Panda:
Death knights! 1+ mil HP blood DK in pvp was beyond broken when geared the amount of HP I gained back from skills was stupid, they were the ultimate solo class for just about anything. The 20mil hp bosses that dropped mounts? no problem! took about 10mins to kill it but the amount of rage people gave when they saw you comfortably doing it was unreal
Above all the people I've met and guilds I've been in is what made wow, the combat now days is pretty basic although it was enjoyable. and while it's never been as balanced as I would like it inducing a fair amount of rage at times I had a lot of fun learning different classes. I had great laughs and exciting times, I had sad times and disappointment and wasted hours gathering gold only to spend it on stupid crap WoW has evolved and moved on from my personal preference of game but it will always stay strong in my heart.