The worst is Legion. (for introducing everything that’s wrong about current WoW)
Then comes BFA. (for amplifying it)
Shadowlands is third. (for sticking with it)
I’m gonna go beyond a top3 and say that Panda and everything that came after I heavily disliked (excluding WoD as I didn’t play that one). Panda for how many keybinds you had to have for PvP, and how Class design turned out. Legion for horrid class design and progression systems. BfA for horrid progression systems. Shadowlands also for the same reasons as Legion, but with a different dressing.
Still, there are some stuff that I enjoy, but I don’t know how long that’ll last.
Edit: Again, gonna go beyond the top 3 and say that vanilla-cata I really enjoyed, for many different reasons, although the main contributing factor is that back then, I was still very fresh to WoW in general. The game immersed me more, and in gaming, nothing is going to be as great as your first time. First time seeing the zones, doing the quests , finding easter eggs, reading the lore, leveling up, experiencing the classes, dungeons, bgs, wpvp, raiding, arenas, getting my first full clear in a tier,high end raiding, high end arenas… But since Legion, WoW to me feels like a watered down version of what I already saw.
Only Shadowlands because the others were better. I’m enjoying Shadowlands a lot more than the other 2. I chose these as the worst because Legion was the downfall imo. Too much borrowed power through artifact weapons which then carried over into BfA and beyond. Shadowlands no where near as bad though imo.
My top 3 favourites are;
MoP
TBC
WotLK
Actually I liked WoD too… and cata. I dunno, too many memories!
Worst Expansions:
1: WoD - Didn’t ever play. Marketing didn’t convince me to subscribe.
2: Legion - Didn’t play it. Didn’t like the idea of Artifact Weapons, so didn’t buy or subscribe. Have gone back and played through, the content was good fun. But because of it failing to convince me to buy it, I can’t place it higher up the list.
3: Cata - Failed to keep me interested in the game and unsubbed after 1 month.
Favourite Expansions:
1: TBC: - My prime in WoW, have many fond memories playing this expansion.
2: BFA: - My favourite modern expansion, best recent storyline and really felt like I was on Azeroth again. Only reason it’s not in position 1 is because of Corruption.
3: Vanilla: - Just that feeling of exploring that new world. The learning curve the first time that you were doing it.
BFA just had to much farming and to many annoying systems that took alot of time, Cataclysm I really hated the raiding scene in and Warlords of Draenor was abit too short all though I really did enjoy the two final raids.
I think its unfair to Shadowlands to pass jugdment on it before we have seen the entire expansion. If I would pass judgment on previous expansions based on their first tier they would place totally different from their final standing.
So far the game has taken a step back and is alot less grindy which is a major upgrade from both Legion/BFA. The first raid tier is also really good compared to some previously first raid tiers.