I don't like #163 - not exactly sure why but I think it's related to the ab being so small in the box. I think any theme with the B laying down is out. (there were two founding partners of the company back in '96, and the "B" passed away in 2003 - something which this logo theme is strongly reminding me of).
#161 is better. I don't like the size differential between the A & B. The size, style, and spacing of the text portion of #161 is very good.
#183 - I really like this one, but it is way too close to being a copy of #45 by aremmai. You've taken the main elements of #45, which is my current #1 ranked entry, and combined those with the best of your #171. It's very nice, but I just wouldn't feel right about selecting it.