With classic out and everyone being able to see all the zones in their pre-cata version once again, it occurred to me that I preferred some of these in the vanilla version but also realised cata improved many in others.
The ones that stand out as being ruined imho are:
1. Redridge Mountains
2. Thousand Needles
3. Eastern Plaguelands
4. Tanaris
5. Alterac Mountains (basically removed and next to no quests or lore there anymore).
6. Loch Modan
While the improved ones are:
1. Silverpine Forest
2. Hillsbrad Foothills
3. Duskwood
4. Searing Gorge
5. Stonetalon Mountains
What do you think? I'll edit in reasons later or in comments if there are questions. Just had the thought on the bus home!