I have tried all of them at one time or another. Here is my take,
Vista- Very well built fixture, good lensing and easy to service.
CAST- Very well built fixture, also good lensing and easy to service-cost is a bit higher though
Kichler LED- Build is fine and pretty clean, no lensing (you will see individual dots from the LEDs on the stone), the chips they use are cheap you will see chips vary in hue from a green, yellow to purple. This is a result of poor binning in the 2700k spectrum. I have used them twice and my both customers hated them and had me remove them. I don't recommend them until they make some major changes.
Focus- I have not used the focus lip light yet, so I can't comment
VOLT- Heavy, decent built fixture (albeit a bit bulkier than it needs to be),good lensing and easy to service.
Integral- Cheaper build-(non-enclosed lamp), no lensing, servicing is easy which will definitely be required with an open lamp-if using LED lamps I wouldn't recommend.