I think the avatars look better in the blue background, the blue tends to be more easier on the eyes also
I like the blue. But everytime I log out, it resets and goes back to green. So I ususally don't bother to change it. The green is fine, but I switch to the blue whenever I get bored.
There are many threads like these.. please search before you open again. Anyways - for me, it's green.
Even though my favorite colour is blue, I have to say I have grown accustomed to the green theme of DP..really suits it well. When I see the standard blue VB theme, it makes me think of a new forum or a noob forum, the green theme makes DP seem more professional. ^^