Being a raider in WoD was nice. No endless busywork to keep up with the demands of raiding, heck, even consumable farming was nonexistent with the garrison garden providing the herbs for consumables. But i can imagine being a casual player in WoD was pretty pointless given that the expansion had very little to do outside of raiding. Garrison missions were also a pretty idiotic expansion feature that came with no meaningful gameplay, but that came to stay so that complaint continues being relevant to date. BfA is the opposite, being a raider sucks - i've spent more time doing mind numbing busywork than actually raiding in this expansion. Consumable farming was awful especially at the start of the expansion, AP grind never ends, much of the gear comes from M+, or in case of 8.2, world quests because benthic. I mean, why the fuck are world quests and island expeditions relevant content to cutting edge raiders? From what i've heard, casual players seem to like having stuff to do though. Classes were also overall better in WoD. Raids themselves have been good in every expansion, that's the one thing wow excels at.
As an expansion WoD was half baked, but i liked playing in WoD much better than i like playing in BfA. The defining characteristics of BfA to me are busywork and dumbed down classes. And, i guess i'll also be remembering BfA as the expansion where i finally quit after 14 years too, i highly doubt SL will make drastic enough changes to the right direction to bring me back to the game. I don't think i've ever called any expansion definitively the worst, but to me, BfA was the worst expansion so far.