I'd have to say Shibuya. I find Harajuku fashion...I don't know how to describe it... It's like you're asking for attention. Just like Punk clothing in america(not the style, I mean the attention part) I, though, find myself wearing punk-esque clothing more often than not, not because I'm looking for attention, but because I really like alot of the stuff.(studs, skulls, crazy hair, the works). Me saying this, is contradiction, I don't know...maybe I am just a confused case.

Harajuku is all about "SEE ME" which is itself not bad, sometimes it makes for an interesting afternoon so see how wierd some people can be

Hmm...from the clips on those two videos I would have to say that I prefer Harajuku. Some of the outfits are just plain crazy, but some of the girls looked nice too. :) Shibuya is just a little too conventional for my liking.

Is there are kind of sweet, vintage fashion in Japan that is vaguely rock-inspired but not too punk? Or would that still fall under the 'harajuku' bracket?

I'd say it would fall under harajuku if there was anything. I remember seeing some pretty (awesome) modified kimonos a while back, though, I don't remember where -_-.

in winter most people are wearing big coats but the teens in Harajuku are still showing off their fashion despite the cold

i like shibuyas but harujaka is nice too cuz its different but thy have a lot dresses which isnt my style

I would not wear any of them (guess why), but i would prefer if my J GF (if I had have any) would wear more feminine and classy Shibuya...

Shibuya becouse it's my style

i think i prefer harajuku fashion because it really different and you don't see that kind of fashion everyday....unless you live there xD
but i don't know i just kinda like most of japanese fashion