
IMHO there's a distinction between 'best', 'favorite', and "most influential"; also between "comic artist" and 'cartoonist'. (A cartoonist writes as well as draws.) We can pick out some of the influential giants, and the great line artists, and the clever strip-writers. But it basically boils down to favorites. Mine, in no special order:
Windsor McKay (Little Nemo)
J.R. Williams (Out Our Way)
Alex Raymond (Flash Gordon)
Carl Banks (Uncle Scrooge)
V.T. Hamlin (Alley Oop)
Herge (Tintin)
R. Crumb (Zap)
Gus Arriola (Gordo)
Juan Ryp (much stuff)
Jim Steranko (S.H.I.E.L.D.)
Basil Wolverton (early MAD)
Larry Todd (Dr. Atomic)
Stan Lynde (Rick O'Shay)
Trina Robbins (much stuff)
Barry Smith (Conan)
Rube Goldberg (of course!)
Wally Wood (early MAD)
Rand Holmes (Harold Hedd)
Jack Jackson aka Jaxon
Jean Giraud aka Moebius
Rich Corben aka Gore
Rick Griffin (Murph the Surf)
J-C Forest (Barbarella)
Spain Rodriguez (Trashman)
Bill Holman (Smokey Stover)
S. Clay Wilson (Checkered Demon)
Many many more, of course. These are from the top of my head, creators who blew my mind somehow-somewhen. But how could I leave out Harvey Kurtzman, Hal Foster, Al Williamson, Shari Flenniken, Al Capp, Art Spiegelman, Ron Cobb, Joost Swarte, Steve Ditko, Osamu Tezuka, Milo Manara, Jack Chick, Gilbert Shelton, ad infinitum? Whatever turns us on, is GOOD.