Is Fluidmaster good or is it best to use the manufacturer's originals?

I haven't had to service a toilet, but either one should work. Fluidmaster seems to get good reviews online.

Fluidmaster makes excellent replacement parts. It's the only brand I'll use when I have to fix a toilet.

Fluidmaster makes excellent replacement parts. It's the only brand I'll use when I have to fix a toilet.

There was a guy I used to work with who had some medical condition whereby he had to pee very often. He nicknamed himself: The FluidMaster 

I've had good experiences with their fill valves and 2" flappers but the 3" flapper I picked up didn't fit the toilet I installed it in. Now I think it's more of an issue from the flush valve seating the flapper than a issue with the product itself.

I'm pretty sure the Fluidmaster fill valves are the OE fill valves used by some manufacturers but rebranded.