Which castle-to-imp transition do you find the most awkward and/or difficult playing as pocket in a 4v4/3v3 :?: Meso-civs and civs with workable paladins are excluded. Of course assuming you have been making knights (mixed with camels if possible).
I would say (in order) Koreans, Mongols, Celts, Goths. Also, WHY ONLY 10 OPTIONS IN A POLL?!