I'm not on verizon anymore. (Wish I was) but for my money the droid charge is. But if you don't need LTE and don't mind moto blur (though I hate it admit I have returned a phone over it) then the Droid X2 might be your most powerful out there. But only for a short time. To sum this drabble of mine up I'd say Droid Charge. Played with one the other day. It is an awfully beautiful phone. Just two cents hope it helps.
I heard that the os layer that samsung uses is not very well done, that saying, I know a lot of people who do not like Sense. I am excited to play with a Charge. I really wanted the Bionic, but seeing as how the phone is still not out, I am glad that I didn't wait.
I agree with everything zxc314 said. Main reason not to go with the Thunderbolt is its abysmal battery life. Neither UI skin is that great so I'd recommend rooting no matter which device you get.
I have been really surprised by my Verizon iPhone 4. Gets better signal in the office than my coworkers droids (Incredible and X). I haven't been happy about the segmentation of android, reminds me too much of Windows Mobile. Plus, there are better phones than the Thunderbolt out now (Samsung Charge, the dual core LG). If you live in a 4g area, maybe the Thunderbolt wins based on LTE, but otherwise, Id get the iPhone or the Incredible 2.
I have not been thrilled with my TBolt. I like the speed on 4G but it is sluggish and the firmware screw up really is annoying.