Which phone should you get the Droid Incredible or the Droid Thunderbolt?

There is no Droid Thunderbolt. There is the HTC Thunderbolt.

I would recommend the Droid Incredible 2 which came out in the past month. It dose not have 4G like the HTC Thunderbolt but It is far more powerful than the Droid Incredible and will be worth your while.