People aren't really binary like that ... "competent" or "not competent". It's all mushy and complicated. Some of the most competent people I manage at some kinds of tasks are basically a net loss at other tasks. The pleasant ones are lot easier to work into diverse tasks and get a "competent result" even if it is more messy than just tossing them a task an forgetting about it.

I think that's orthogonal to pleasantness. The tasks I have in mind revolve around coding, since that's my job. If the job extends beyond coding, to gathering requirements or coordinating a team, I'd be more inclined to agree. But they don't, for what I'm thinking about.

Well to keep it positive, I'll just say that I find working with competent people to be quite pleasant.

100% agree to strongly disagree :)

Until in their efforts to be competent, they be unpleasant to the wrong person--and now you have a new and different and harder problem.

Arguably, that's being incompetent. If their task involves a social interaction, then to be competent at it they must know how to successfully manage that too, even if they are generally unpleasant.