I've selected one candidate over another for some impression they were marginally more impressive, but the only reason I have ever given a hard no was arrogance.
I've worked with arrogant devs before (and anecdotally they've written some of the worst code I've ever seen - usually because they complicate the hell out of things because they think they are smarter than they are) and I loathed it.
Be confident in your abilities but don't be a dick about it and always accept the strong possibility that the other person may be right.
I saw a phrase I liked on here a while ago, "strong opinions weakly held" that summed it up nicely.
