I'm from the Midwest where the "accentless" American English is. I don't mind British accents, though some are barely recognizable as english. Cockny and highland brogue to name a couple. America has certain accents that make understanding difficult as well. Hillbilly, deep south, and hell if I know what half those folks from "Jersy Shore" are saying.
Then you have American army english, that's mostly grunts, interspersed with swear words and technical terms. No one I have ever heard could swear as much as M1 tankers. Example's being "Where the blankity blank is my blanking fire blanking support...BLANK!!..Blankin get my blankity blank blanking Sargent Blanking NOW!" Roughly, from what I remember anyway.