I have both. Thunderbolt is superior in every way except battery, but 1600-1800ma batteries are on the way. As of right now, you can lock in to the unlimited 4G data plan for $30 per month, as this unlimited plan will go away by midsummer at the latest. If you like a stock phone, HTC Sense 2.0 UI is infinitely more tolerable than motoblur. If you dont like a stock phone and prefer the customization rout via ROMs and such, S=OFF is win, and moto locked bootloader=fail. Developer support for the Thunderbolt will equal, possibly even surpass, the OG Droid 1, and developer support for that device far exceeds any other device on the market except maybe the Nexus 1 and Desire.
The Bionic will be a fantastic phone, but I fear the release may coincide with the introduction of tiered data pricing. Plus, if again you are the customization type, the history of moto locking their bootloaders will be something to think about, as this will prevent custom kernals.
The Moto Targa is supposedly a quad core device releasing later on in the year (3rd or 4th quarter release?) that trumps any device, regardless of manufacturer or carrier. Seems to me that once this device hits on vzw, it will render even the dual core phones obsolete.
But, as I told a friend of mine the other day, if you wait for the next device that is supposed to be the best, you will be perpetually waiting forever. Thats why I say go with the Thunderbolt, as it is superior in every aspect to the droid x.