The 66 rc2x is dual coil, 66 light is coil in the left leg and air preload in the right, 66sl is all air with positive air in both legs/negative left leg and par. Im not sure what the vf is.
If weight is an issue then the sl might be the ticket. If you dont care about weight the coil versions will be a good choice. The sl also has adjustable travel through the use of air pressures where the others are fixed travel.