I'd, gladly, substitute 'mercurial Spaniard' with an honest 'thank you'. To each their own when seeking friendship. Finding honest, humble friends, in my opinion, supersedes worldly, articulate fellows.
Honesty and vocabulary are not even loosely correlated. I agree that, given the choice between the two, you should choose honest, humble friends.
But if you're ever judging someone's worthiness of friendship because of their Flesch–Kincaid score (whether it's too high or too low!), you're doing it wrong.