41 male, here.

Looking back to when you first started World of Warcraft, what was it that drew you in and got you playing? Were you already a Blizzard follower through Warcraft / Diablo?
Mostly, Blizzard's rep. I had tons of fun in Warcraft 2 & 3 and Starcraft and they were very solid games. Diablo was OK but it wasn't really on my radar for reasons why.

Out of the entire life cycle of World of Warcraft, what event was the most memorable to you personally?
Sort of split between my first multiboxing group to 60 and my paladin badge-farming group in WotLK before they fucked them over with 4.0.

What is your favorite expansion so far, and why?
WotLK. Was able to 5-box for my own reasons, get enough gear to keep me happy and got to see a lot of the old raids.

What is it about World of Warcraft that keeps you playing?
What it _was_ that kept me playing was that it was fun: the solid engine, smooth combat, good GUI design (addons, mainly), reasonable bar to entry for non-raid content and being able to spec certain classes to do really, really good (aka OP) at certain specific tasks.

If there was one thing you could change in World of Warcraft, what would it be?
Go back to pre-4.0 talents and class mechanics. Secondary choice: make Blizzard stop trying to balance everything perfectly for their e-Sport crap and go back to the versions of each class that were the most fun to play e.g. pre-4.0 paladins, BC hunters, classic enhancement shammies, etc.