I am using a T8 in my CB and a T6 and a T8 in my BBB's.
I really like both. I generally use RBAs, but I love the TFV8 coils. Best I have ever used.
The CB is really big and absolutely chugs juice at 120w with the T8 but the T8 coil I am using is over 5 weeks old and still good. It can also leak a bit. Coils are expensive too.
The BBB is a great tank and the coils are excellent and cheaper than the CB coils. They also last a long time. Great vape at 50-70w and not as bad on juice as the CB.
If I had to pick only one it would be the BBB.