GMs whose character sheet tells of someone who's near perfect, whose only imperfection in power or personality is so minor that it's eye-rolling insignificant and added on as if to say, "There, that's their flaw!" E.g, a master swordsman who's well versed in magic, languages, music and only-moderately capable in guns (that humble pie!), a philanthropist and empathetic in any situation, whose only weakness is his friends in danger. 

If I had known the GM would make a character so strong to play with the rest of us as equals in the game, I wouldn't have created a character whose abilities are like a freshly graduated mage. Then again, both as a player and GM, I like characters who start out weak and mortal, to develop into something else surprising down the line; I don't like to detail out every aspect of amazingness my character could have, esp power-wise, right in the beginning of the story. I feel it's limiting.