Can anyone recommend a better brake fluid?

For the first time ever I had problems with the clutch hydraulic system
in my 94 Maxima; every morning, the pedal would go to the floor, without
disengaging the clutch.

After manually returning the pedal, the clutch would work for the rest
of the day without a problem.

I took apart the master cylinder and found that the seals where in
perfect shape, no visible wear, but the inside of the cylinder was full
with crude that looked as if there were drops of grease in the fluid, i
think that was moisture.  This crude apparently did not allow the valve
at the end of the piston, to work correctly, thus causing the problem.

The cylinder itself is in top shape, no visible marks or wear
whatsoever. What concerned me is that the coating on the cover of the
valve at the end of the piston, the piston itself and the spring, showed
signs of chemical attack, the coating is gone in patches.

I rebuilt the cylinder with new nissan parts and in an environment as
clean as possible.

Since I had changed the fluid several times, and it never changed color
significantly, I am doubting the quality of the brake fluid I use,
Valvoline SynPower synthetic.

Can anyone recommend a better brake fluid?