the guy that made matrix chess
underated

I really don't have time to closely pay attention to the GM world. Besides, once your OTB rating goes over 2200, differences are pretty much a matter of degrees.
Here is an old quote attributed to Nick Rossolimo (an old GM from the 50s & 60s and a guy who helped systematize the use of 3. Bb5 against the Sicilian): "Masters are like elephants. There are big elephants and small elephants. You still can't toss an elephant."
I hope the attribution is correct, because it's a great quote...and a great excuse!
Which grandmaster is the most underated?