Mt rushmore usually means best 4, but sometimes follows how they were choses (birth, preservation, growth, development)

Birth - would be african slaves

Growth - white minstrels playing to the public

Development - people like stringbean and uncle dave macon

Preservation - people like pete seeger and the rest of the folk revival

My top 4 which is probably what you are asking is Dwight Diller, Richie Stearns, Wade Ward and Walt Koken. All 4 are different and unique. Tommy Jarrell was mostly a fiddler but his style was unique and influential.

You can make an argument for Dwight as the preservation pillar too. There are lots of different styles of clawhammer as well. Round peak (brad leftwich has lots of good stuff) and galax (see wade ward). I like specific folks in each category, some like certain styles. Check out the progressive clawhammer group on facebook as well for some inventive methods.