ah, good question!
I think "boasting" is the correct word. Loud, self-important, maybe pretentious? But not in an unfriendly way, rather in a silly one. Think of an overdone John Wayne gag.
To be honest, I think this has more to do with subconscious cultural references, rather than the sound itself.
E.g. the sound of en_us always evokes Italians speaking in gibber-american-english[0] rather than some martin luther king jr's speech.
I didn't want to excessively prejudice the answer, but to me English sounds like a relatively harsh language. Every other language always seems to sound smoother, except maybe really fast Spanish and to some extent Russian, which, if not "harsh" per se, often sounds angry to me, or with all the slurred-soundings Zs in it, drunk. No connection to the stereotype of drunk Russians intended; one wonders if there is a connection there, though. (Though it could also come from reality; from what I've seen of the statistics "drunk Russian", alas, has a lot of truth to it.)
What really opened my eyes was German; if you read German with English phonetics, it sounds awful, though it's sort of fun to do. But when it is read or spoken correctly, it's a more soft, flowing language than English.
