From what I saw from GA, the best spot to be is around any of the branches.
We were crowded around Larry's branch, and it seemed that Edge and Adam stayed mainly over on the RED Zone side near the top of the tree (slightly outside the Zone), and Bono seemed to like to come to the GA side a lot more than the RED side.
During the JT portion, they spend most of their time on the main stage - so everyone is pretty much equal at that point. When Bono and Edge come back down, though, it seemed the RED Zone got more of their attention.
The only "bad" spot to be in the RED Zone appeared to be the "trunk", as you'd only be near the guys as they went back and forth between the stages - but, still, that's not a bad spot. As someone else said, once you're that close, there's no real "bad" spot - it just comes down to who you want to be near.