I played with a few friends' phones and I have to say I like the Win7 UI and I've always liked the Zune music player, so I'm going to go with windows phone 7. Of all of them, I'm going with the Samsung Focus and I'm going to expand it to 40GB and load it up. Unfortunately, it's out of stock at the moment
WP7 is retarded in file management so you have to use their zune software or whatever its called on your desktop.
if you decide to reuse your micro sd elsewhere it won't work cause of the way its formatted.....which is irreversible
unlike android, I can just plug and play my SD cards whenever I like or need to