As someone that has everything capped. The addition of mounts you have to unlock to get to certain places is both frustrating and unclear on when/where to acquire them. The roll mechanic is great however there is a ton of shit you simply don't get a heads up on the way I'd like to be able to make meaningful gameplay. The overcomplication of debuff stack limits. Pretty much all melee being better than ranged at every aspect of the game. Lack of a true endgame. Lack of gear making a large difference in character progression. The lack of a Tank healer dps structure means you're constantly having to deal with sporadic boss and trash movement, conditions going all over the place uncontrollably and making fights seem hectic and uncontrollable. WoW exists and is better in almost every way except art and world quest progression.
To me WoW starts at the endgame, whereas in Guild Wars 2, I find that world completion (questing) to be the biggest part of the game. Which is why people tend to get world completion and quit. WoW keeps you engaged with more focus on it's endgame and meaningful gear choices.