Bascially there are 2 types. Elastomere and fluid. Both are good. Recently I learned of a flip side to the fluid style damper. Some feel it may create a bad harmoinic on high rpm engines that are on/off the gas a lot (like road racing and drag racing).
The argument goes something like this. The fliud element of the damper holds some inertia. When you let off or get on the gas the fliud wants to stay at it's current velocity and balence. Until it changes to the new rpm, it's very slightly out of balence and thereby it's creating a bad harmonic. Sounds good, but may not be anything at all.
I'd run the FRPP M-6315-A50 damper for a 50oz balence engine or a M-6315-C351 for a 28.2oz balenced engine. Both are SFI 18-1 and both have a removable weight if you go to a zero balence style internal balence setup.