Agree with not being stiff. We do like the craic and can talk for days (often shite, as you are about to witness).
All nationalities have their good and bad points (generally speaking of course as no nationality is one monolithic group). So with that being said,
My favourite nationality are Scots. They just see through bullshit better than anyone else imo (no nonsense, think that's why they make great football managers).
The English to me always feel like the grown ups in the room. Sensible people, very grounded and seem to have more common sense than the rest of us. They are the nationality I'd nominate to represent us if aliens visit us.
Welsh, always seem to have big booming voices. Cannot think of a softly spoken Welsh person. It's the valleys doing I think. They also produced my favourite boxer Joe Calzaghe who is the classiest fighter I've ever seen.
Germans don't have much of a sense of humour but they are very efficient (best cars)
If you want honesty and directness ask a Dutch person
Canadians are very polite
Americans (two versions for this one), the people in the coasts, sensible folk, those in between, we are hiding them if aliens visit us as we'd get exploited as a species otherwise.
Aussies are everyone's mate and I love how they often use nicknames.
Kiwis, like the English very sensible, and without question they have the best (beest) accent (the standard English accent a close second..would much prefer to pronounce car "Ca" instead of "Key-arr" as I say it).
Japanese, very orderly, and focused. Their mind isn't full of emotions which leaves plenty of room for thinking straight which results in them making us all great video games.
Scandinavians, all similarly cool as a cucumber to match their enviroment. Just completely unflustered folk.
French, passionate, full of flair, and I admire their love of the French language as they seem to be the one nationality that refuses to submit to English as the dominant language (indicative of this is Zidane who flat out refuses to speak a word of English in interviews despite knowing full well what the words mean)
Italians, even more passionate, and they seem to excell at everything. Food, fashion, cars, sport, art, architecture... immense.