Dominoes out of the box is 12 bars 12 buttons. That said, each toolbar can be customized just like the old Bongos setup. It would be rather asinine of the author to make his next-gen product less feature-filled than its predecessor.
What little I do know of dominoes is that it was built to stay as near to the Blizzard code as possible, so it requires less overall maintenance and patching for the long haul. I don't know enough about other bar sets to say that.
Plus - given the longevity that addon author has had with WoW, I'd consider it a stable long haul of a tool. Since I can't speak about the other tool bar add ons, it's a reason I have comfort with suggesting Dominoes as a suitable replacement to Bongos.
--McBean