"He who marches out of step hears another drum." ~ Ken Kesey
The only waterbased black I've used is Matsui Spot Black. Even after repeated washings it's jet black.
Proper WB black is the blackest of all blacks.Up your pigment load if you can, or better yet, try a premix black.
We use the CCI spot black every day and it is as black as any of the waterbase inks come. It works great for us. Out of all the blacks we tested it was the blackest. GG is also nice and soft but not as black as CCI.