re: What was the best WoW expansion?

In my opinion, TBC was the best.

Everyone typically has Vanilla high on their list, and deservedly so, but a lot of that is just pure nostalgia. If you go back and play on a private server it's kind of a pain in the arse.

Vanilla, I was never great at the game, I saw a fair bit of raiding, but mostly focused on PvP and got rank 10/14 as a young teenager.

TBC came around and I became a hardcore raider. To me, nothing will ever hold a candle to Karazhan, SSC, TK, BT and the Sunwell. But then again, in late WOTLK / Cataclysm I started focusing back on PvP, and had limited exposure to hardcore raiding after that.

If I had to rank them...

TBC
WOTLK
Vanilla
Cataclysm
MoP
WoD

I'd have WoD higher than MoP, but garrisons sucked and they have absolutely ruined PvP.