To put it simply, what quality do you look for in a friend?
For me whether I can trust them is pretty huge. Since I tend to be fairly open with my friends, I don't want them blabbing to my colleagues things I said in confidence.
Another is intelligence. They don't have to be able to discuss Quantum Theory or anything, but I should be able to have an intelligent conversation. Honestly I have stopped talking to a few people over the stupid things they've said, especially when they are just parroting untrue statements or when they don't even understand what they're talking about.
So what about you?