Colored gems, Meta gems, socket bonuses, multitude of enchants, reforging, profession-specific bonuses (f.e. Tailoring attack power proc on cloak in Cata), glyphs, old stats (spellpen, hit, exp, etc), PvP stat (Cata resillience), class sets, gear with natural sockets on them, cool trinkets, cool weapons, Tol Barad / Wintergrasp, no mandatory dailies (excluding TB and WG if you really wanted a piece of gear that won’t outlast the very season you’re in), better class design, overall better progression systems
Unique sets for each class (I mean the look), specific gear for pvp and specific for pve, good class/spec design, alt friendly design, a game that actually looks like WoW. Mostly that’s it.
Just that feeling when offline, "oh next time I go to WoW I will do this thing , then complete that thing. " Now I just go online look at the blue questionmarks at my covenent and sigh.
This in a nutshell. I had a things I wanted to complete, now I have things I have to complete and things I can ignore. There is little I want to do at the moment.
Cata: Winning TB and the global chats in Org filled with people forming raid groups to go do the mini raid.
MoP: Having something to do every day with world quests. I enjoyed logging in, setting out on a goal and achieving it all by myself, external to raids and PVP. Just solid world content.
WoD: Casual raiding with my guild. The raids were super fun.
Legion: Artifact Weapons. AP sucked but the weapons themselves, at least early on, were pretty neat.
BFA: 8.0 and 8.1 wasn’t as bad for random BG’s. That’s about it.