I guess I should finally enter this thread. I'm playing since Vanilla EU-Release, and while my account was not always active, I played every expansion extensively, though the last time I did organized raiding was back in WotlK. Just activated my account again after a hiatus of several months.
Always played a Paladin since Vanilla, and boy did this class change since Patch 1.2. Anyone still remember Seal of Fury? Righteous Defense? Divine Intervention? Blessing of Light, the old Blessing of Sanctuary, the old epic mount quest, the quests to get Redemption (met lvl 60 paladins who didn't do the quest and couldn't resurrect) the old Blessing of Kings which was completely insane with +10% on all attributes and was hidden as ultimate in the Retribution tree (Funnily, Maximilian of Northshire buffs you with the old version of BoK in the new questline in Highmountain). I can't remember how often that added, removed and reworked Sacred Shield. The old auras are now long gone, as are all seals. Excorcism and Holy Wrath are gone, as is Hammer of Wrath. Sense Undead, anyone? Man, the old Seal of Command was so frustrating, and it was the only way to do any kind of significant damage pre-TBC.
My second most-played class was Mage, and it didn't nearly change as much. Though, I tried to play Fire in Legion and I absolutely HATED it. Why is there even a mana bar anymore? You have unlimited resources, you shoot more instant pyros and other instant crap than regular fireballs. It honestly feels like a gimmicky, flashy Third-Person-Shooter or something and is extremely boring to me.
In general I'm very critical of many things Blizzard did to the game over the years. This thread seems like most people are fine with the status quo, but I literally can't bring myself over to level even one new character from the ground up, the leveling is atrocious in every way. In the same time, I had a blast playing on several private Vanilla servers leveling several different classes.With all the tediousness and missing QoL-improvements, the vanilla questing feels vastly more rewarding and immersive than the linear, empty, non-challenging Leveling of today, which is also full of cutscenes, dumb pop culture shit like in Westfall, Redridge, Burning Steppes, Uldum et, and lots of gimmick quests. Every zone is almost completely self-contained and feels like a level in an underwhelming Single-Player RPG instead of an massive, open world. Was it annoying to travel around the world with boats and gryphons back in Vanilla for hours? Yes, sometimes, but it made the world feel real and massive and connected. I could go on about many other things like the vanished Server community, linear tube dungeons, vanishing of CC and threat as relevant PvE-mechanics, too much focus on collection fluff etc.
Legion was a step in the right direction, with the artifact, class campaign and profession quests making use of the whole, vast world that mostly lay barren otherwise. Still don't understand why they don't implement world quests and legion invasions in other zones instead of the extremely cramped and honestly stale Broken Isles zones, which also lorewise would make much more sense.