Both formats work well, and will give you great results.
I would start off on the Reeves classic FB routine as a starting point. It is a pretty straight forward program. You can alter the rep range slightly if you are so inclined and work sets of 6-10 as opposed to 8-12.
Once you have spent some quality time with the program you may find you need just a little more rest and at this point going to an A/B program can work well.
Still, I have worked myself into the ground on A/B programs in the past.
You must allow time to adapt to FB work if you have never done it before.
If you have not done so, read the classic physique challange thread. There is a lot of good info in that thread on FB work.