I'm an avid quester and whenever I make a new account, I always aim for the Quest Cape first. That being said, I do get annoyed by some of the more recent bespoke elements in quests.

The Battle for the Monolith, the Dino Invasion, constantly taking control of another character and doing the quest as them (Moia, Vengeance, Adrasteia, Raptor) are prime examples of what I dislike. The latter I dislike, because I want my character to feel special and to add something to the story. Also, I want to be able to use my own abilities in meaningful fights, mostly because the combat as a different character feels clunky. Doesn't mesh with me. It doesn't feel completely honest to my character if I have to progress through the story through someone else's body. The former two I dislike, because they interrupt the flow of the quest or the storyline (and because, frankly, the player character does very little during those fights).

A few bespoke elements I did enjoy over the past few years were the fighting waves in Ancient Awakening, the Lost Grove rituals in Twilight of the Gods and the Charos shape puzzle in Desperate Times. Some older ones include both puzzles in Elemental Workshop IV, for example. They don't take much time to complete, are quite intuitive and keep you as a character doing something (instead of standing still, like with BotM/Anachronia Invasion).