Slowie you have some hard decisions to make

wait for the gs2 (good) buy the charge (good) go to Sprint (if coverage in area is good you are good to go)
I think the Charge is a great buy because it has a great dev community beginning to back it. That's what's kept me on the Droid for so long. So that's a definite bonus.
Galaxy SII will be the best device of 2011 (my opinion) so its definitely worth waiting for.
Sprint has an awesome Android line up so that's a great move if you move over (assuming coverage is great in your area)
I say wait for the Galaxy SII it runs like butter. No device can touch it.
Sent from my Droid