I would use whatever fill valve it comes with. Everybody has an oppinon though. I've installed thousands of them though, so I'm going to notice that I hardly ever have a call back, ever.
I would not use a Fluidamaster 400A in a TOTO. Ever!
TOTO uses three fill valves, and they all work fine.
Some do come with one made by Korky.
The Fluidmaster 400A is much noiser, has more water hammer, and it overfills the bowl by a bunch. The 400A would wind up costing you a lot on the water bill.