I have the Baby Beast, Big Baby Beast, and Prince tanks. But although RBA's are available for all of them, I don't use an RBA deck on any of them, so will leave that consideration to others.
As far as the tanks, I much prefer the BBB over the BB just for the added volume. But my favorite of the 3 is the Prince. Large volume and I really like the locking button on the fill cap and the larger fill hole. Good flavor and clouds. Having said that, I do have one juice/flavor that has gone back into my BBB cause it just "tastes" better to me.
The wattage for the Prince varies, depending on which coil is used (and juice used IMHO). The Q4 at 0.4Ω is my least favorite and I ran (notice past tense

) it around 56 watts. I am currently split between the X6 0.15Ω and T10 0.12Ω coils and finding little difference. The X6 around 75 - 78 watts may offer a little more flavor then the T10 I run between 78 - 88 watts. But that may be more the difference in juices then actual performance. Some say they are liking them at higher wattage, but I am fine at those wattages which may extend coil life....but who knows for sure?
I'm finding the Prince to be a really good tank, especially for somebody like me who struggles with building/wicking. Worth a try!