Westfall I loved. Duskwood wasn’t bad. Winterspring was OK.
I actually feel that zone design was one of the weaker aspects of Vanilla. In life I love Fall, Winter and Night.
There wasn’t a lot of that in the game. Expansions did a great job fixing this - WoTLK has some great zones, WoD had an amazing Horde zone for their stronghold or whatever it was called, and Legion had a great old-timey spooky zone that I can’t remember the name of. It was by the old giant mansion area… BC even had one small little area - but I can’t remember where it was. You had to kill bears and spiders and demons and you got the quest in this spooky tiny village near the water.
Vanilla I feel was much weaker in their zone development. I know Undead has some darker zones for their starting areas, but they never quite captured it.
Going back to the Vanilla world is actually the only real disappointment I can think of in Classic - because I won’t be able to explore some of the best areas in the game anymore.