Characters with "character" are good, but not when it makes you wish you had anyone else to have in your party.
I somewhat disagree. There should be characters of all sorts, including asshole ones. You aren't forced to take any of them. Durance in Pillars of Eternity is a great example. He's a complete piece of shit - racist, misogynist, petty, vindicitve and not nearly as smart as he thinks he is. He's also an incredibly memorable foil to both you and Eder. He's easily my second favorite, precisely because he's so awful.