I am personally waiting for the Bionic, but if I had to choose today I would go with the Charge.
I heard it gets the fastest 4g speeds and from my little demo of it, it's a great phone. My only knock on the device is TouchWiz, but I was going to replace that with LauncherPro anyway, if it let me...
I had bad experiences with multiple LG products so I refuse to buy from them again. And the Thunderbolt battery life is a deal breaker, it's even worse than my Incredible my friends say.
I am having the exact same problem as you haha. I keep going back and forth between the charge and the thuderbolt, and cant wait for the bionic because my phone my explode tomorrow. I finally decided to go with the thunderbolt and here is why:
HTC Sense (personal preference)
Kickstand (its a little thing, but i like it)
Front Notifying LED (the charge does not have a front led and it is something i really like to have)
In my opinion the thunderbolt is faster based on the test ive seen and it has more ram
Samsung has had alot of issues with updates
HTC just confirmed that the thunderbolt will be getting gingerbread in september
It's all personal preference. The charge has a better screen and an hdmi port, but i dont see myself ever using the hdmi and I choose speed and memory over how nice the screen is.