I enjoyed Legion thoroughly.
Getting bad leggos was a small dampener but I didn't raid a lot so it didn't affect me a lot. But the stuff I loved was plenty:
-Suramar, story and the city itself
-Artifact weapons and collecting their appearances
-class mounts
-Mage Tower
-Story was fun even if parts were annoying ("Tyrande my love!"")
-Music even if a lot of it was a bit too bombastic at times
-Huge continent to explore with many secrets. Loved the grappling gun in Stormheim. And it was actually fun to explore until we got flying later on. Yes, even Highmountain.
-PvP tower dailies and outside arenas
-Cool community solved puzzles
-Unique class campaigns
-Fun and varied raids that were huge and let you explore
-World quests were very varied and diverse unlike later installments.
-Shaman: Gust of Wind
-Demon Hunter leveling experience
-Invasions pre-event. Was fun zerging the bosses with hundreds of other players.
Not so fun parts:
-Artifact knowledge making things very slow and cumbersome in the beginning, especially if you played more than one spec and class. Got a lot better later on.
-Dadghar talking holes in your head.
-Broken shore. Fuck that place.
-Not being able to target a specific leggo or at least collect them all, being stuck with only 4 out of many possible. Was remedied in the end but then it was kinda too late for many.
-The homogenisation of class spell animations removing many unique animations for many races.
-Antorus Waste was absolutely horrible to traverse.
-A lot of classes were forever ruined. RIP hunter.
Neutral stuff:
-M+. Not a huge fan of timed stuff but I can see why it has gotten so popular.
-Legion invasions. Was rather annoying with those quests popping up all the time and you had to accept them to abandon them. Nice for leveling though.
I probably forgot something but that only shows the enormous variety Legion had. I really enjoyed it even with the small breaks I took towards the end.