PortaPros all the way for sound...I've thought about this question more than a few times, I've also evaluated the PX100s in the mix.
I've tried the Px200s a few times, but always come back to the portapros (which I own)
they sound great, have a really fun exciting sound, are decently collapsable, are extremely comfy, and also importantly, come with a lifetime guarantee. If anything ever happens to them, send them and bucks to koss and you get a new set.
the Px100 and 200, are a little bit more laid back. When I'm out walkin around, I like up front exciting sound over laid back.
BUT: the pxX00 do offer some great things. They fold much smaller and more conveniently, and don't look like you wore them to camp in 1985.
But if you can deal with the teal, get the PPs, they Rock.