I think i'll go for 7
I remember when i installed last year,Windows 7 RC build 7100 71xx , i was actually surprised.
But there was a few thinks i didn't like ( that's a question of taste )
I don't know how to describe that ,but i try : when you move your mouse cursor over the desktop icons ( not only there ) i wish i could have it like in XP,i mean, no "wawes / shadows " or whatever.
The same when you move the mouse cursor over the C/D/E/F partition. Same think, i hate that

And i don't think there is a way to disable this feature.But like i said " that's a question of taste"
I attache here a link with a picture made in Windows 7,i hope you'll understand what i mean.
ImageShack® - Online Media Hosting
The mouse cursor is right over the MOVIE MAKER BETA icon.