Kurt Kinetic Road Machine is my favorite, has the smoothest operation, and while none are quiet, it is the closest to quiet I have found in a fluid trainer. The leakproof design hasn't let me down yet.

The Cyclops Fluid II is also good but not as smooth or quiet.

Avoid the cheap units like Blackburn. They are pretty crude in operation.

The KK is expensive but you will probably only buy it once.