WQ don't count any less because they were introduced in legion if they did that would mean you'd have to take out dungeons raids quest ect ect from every expan leaving literally nothing to compare as you'd take every thing out unless it was introduced in said expan.
it doesn't really matter if you think there a joke or not you could say the same thing of literally any content in wow depending on how you play. in say mop the whole timeless isle and the barrens were a joke to me as i was a heroic raider and played with a group of heroic raiders in both, if you and your friends are geared enough every thing is a joke.
quality is also totally subjective, which is why looking at whats actually in the game is objectively better then looking at what I or you personally like the most. for example would you say that pet battles are a superior form of content to raids dungeons or bg's just because you like them more?
vanilla had solo/class content that bfa doesn't have that's true but probably bfa has a ton more max level quest lines between the horde and alliance then classic i think but i haven't gone though and actually complied the number of quest.
flight isn't actually content and i dread tbc reps so i couldn't agree there but that's all personal preference, though the rewards were better id agree on that.
wrath had also made the lich king into a cartoon villain who shows up every zone and lets you live for no reason, even then wrath didn't really have to much max level questing. i'm also not counting raids in theses comparisons. as far as rep goes i think you could only get to revered or so in the dungeons then had to do daily's but i could be wrong on that one tis been a while.
MOP was the best expan if you ask me and was the peak of world content.
legion was also above Bfa but we haven't got to the end of BFa yet so it could pass legion.
and finally as far as comparing bfa and legion goes if you just want compared 7.1 and 8.1 they are pretty much equal but weighed in different areas, legion pulls ahead when you take the other patches into account but with the .1 patches the only real thing Bfa falls behind on at max level is questing which is probably because of the horde and alliance split and Bfa has a warfront instead of a dungeon which is subjective on which people would like more.