The Beast line is the coolest looking. Also, probably the heaviest. Maximum power, at the cost of balance and pick-up.
The Belta has a higher than normal sweet spot, but otherwise very conventional. Sharp contour down the spine.
The Kahuna and Diablo are very similar. You really have to handle them yourself to decide between them. The Diablo has a more round, bulging profile.
New in 2006, is the Genesis, which is the opposite of the Beast. Designed for maximum profile with minimum weight.