Here are the CNET reviews for your given list of phones, in the order that you gave them:
http://reviews.cnet.com/cell-phones/nokia-6085-pink-at/4505-6454_7-32569047.html?tag=prod.txt.2
http://reviews.cnet.com/cell-phones/sony-ericsson-z310a-lush/4505-6454_7-32595975.html?tag=prod.txt.1
http://reviews.cnet.com/cell-phones/sony-ericsson-w580i-style/4505-6454_7-32578722.html?tag=prod.txt.1 (White was the only one that had a review).
I like the third on the list personally.
The Samsung BlackJack2 in Blue is really cool too.
http://reviews.cnet.com/smartphones/samsung-blackjack-ii-red/4505-6452_7-32717958.html?tag=prod.txt.3
If money isn't an issue, then get the iPhone!
But it doesn't have video, or MMS...
I'd go with the third on your list personally overall.