After doing some reading...it comes down to
1) RAM - 1GB in the Sammy and 512MB in the Bionic
2) 3G vs. 4G - Sammy seems to be 3G and Bionic is 4G
3) Bootloaders - Sammy should be unlocked and the Bionic is unknown.
For me, playing with my OG, I want as much RAM as possible, seeing as I cannot even answer a call sometimes, since my RAM is so low. I am used to 3G...4G would be awesome though. And, seeing as I love to ROM my phone, it has to have an unlocked bootloader. CM7 will be a BIG bonus.
So for now, I am leaning towards the SGS2. If the Bionic is known to come unlocked...that may sway my decision, even if it does have 1/2 the RAM.