I'll go for Loch Modan as the most beautiful place. For IRONFORGE!

The worse place ever? Plaguelands, both easteran and western. Even the Blackrock Depths fare better. That place is just filled with death and decay. Worse still when we Alliance lost the war of Andorhal, to Forsaken no less!

All the Horde cities are better designed aesthethically compared to Allied cities.

Blizzard Gods just love Horde. /FML