The way 'herbs' or 'erbs' (as some pronounce it) drives me absolutely nuts.
Also, 'mirror' where it sounds like 'meer' drives me nuts.
I definitely prefer British English. Love reading the old Agatha Christie books. E.g. "My word!" The colonel ejaculated, "I do believe that she's dead!"
I have to say, though, my most favourite American accent is the Minnesota one. Fargo helped make it all sound very endearing. Unsure how they pronounce mirror. Perhaps it's 'meer'.