Empire, Vampire Counts, Greenskins and Dwarves on Hard.
Empire on Very Hard.
Currently doing dwarves on very hard.
Had a game of Greenskins on very hard where I was dominating. But then post-Chaos being eliminated, somehow my Waaagh armies declared war on me and start attacking me. They siege and raze my cities, attack my armies. But I can't attack them back. It was terrible and frustrating. Rage quit at about turn 180.