IMO
Both the Bionic and Razr have their target audiences.
If I was in your shoes, check out the two phones for yourself. The biggest difference would be the form factor, screen and battery life.
The Razr is considerably thinner but also considerably wider than the Bionic. I think a wider phone is less appealing but you might not feel the same.
The Razr uses AMOLED vs the LCD pentile of the Bionic. AMOLED equals less bright but more vivid in regards to colors. LCD is brighter but the colors aren't that vivid but is also more visible in the sunlight. It's an even trade off IMO.
You have more options with battery replacement with the Bionic because the Razr doesn't have a removable battery. However, I really don't think it'll be a big problem if you have a charger with you throughout the day or if you have one of those portable battery chargers.
As for dev support, not sure if either will take off with the Galaxy Nexus on it's way. The Bionic has a few ROMS but not like it was with the D1. At least, it has something though. A couple of deblurred ROMS which IMO will make good base ROMS for other developers to use.
Good luck with your choice! If you like Moto, then you'll be happy with either device.
Edit : one more difference would of course be the price between the two phones.