I really liked the questing and overall story of WoD, but after playing through it on 1 Horde character and 1 Alliance character, I just didn't care about it at all aside from doing each of the raids on LFR difficulty once to see it. BfA is about the same.
Legion, WotLK and MoP are my favorites, but Cata is up there too. I played the hell out of all of them throughout the entire expansion lifespan.
TBC was cool, but it just didn't have the same oomph as the others to me. I played it a lot though, mainly because I had to, to keep current with anything and everything still took forever just like it did in Vanilla.
I wouldn't say any of them were "bad," but there were definitely some that were just more fun for me than others.