I've just finished going through the all time rosters of every MLB team.
What I have also done, but not published, is use my cross comparative WAR metric to select the best single season for all the members of those rosters.
From that pool, best single seasons from the All Time rosters of every MLB team from the All Time 40 Man Rosters (the Astros are in the AL, Brewers in NL, for these purposes). Each team has to have a representative.
Catchers
Bill Dickey (L) (1937) Yankees
Joe Mauer (L) (1B) (2009) Twins
First Base
Lou Gehrig (L) (1927) Yankees
Jimmie Foxx (1932) Athletics
George Sisler (L) (1920) Orioles
Second Base
Nap Lajoie (1910) Indians/Guardians
Eddie Collins (1915) White Sox
Craig Biggio (C) (1997) Astros
Shortstop
Cal Ripken (3B) (1991) Orioles
Lou Boudreau (1948) Indians/Guardians
Alex Rodriguez (2002) Rangers
Third Base
George Brett (L) (1B) (1980) Royals
Wade Boggs (L) (1985) Red Sox
Left Field
Ted Williams (L) (1946) Red Sox
Carl Yastrzemski (L) (1B) (1967) Red Sox
Rickey Henderson (1990) A's
Center Field
Mickey Mantle (S) (1B) (1957) Yankees
Ty Cobb (L) (1917) Tigers
Joe DiMaggio (1941) Yankees
Mike Trout (2012) Angels
Ken Griffey, Jr. (L) (1996) Mariners
Tris Speaker (L) (1912) Red Sox
Right Field
Babe Ruth (L) (LF) (1923) Yankees
Aaron Judge (CF) (2022) Yankees
Mookie Betts (CF) (2018) Red Sox
DH
Shohei Ohtani (L) (RHP) (2023) Angels
Pitching Staff
Walter Johnson (1913) Senators/Twins
Pedro Martinez (2000) Red Sox
Hal Newhouser (L) (1945) Tigers
Ed Walsh (1908) White Sox
Bob Feller (1946) Indians/Guardians
Roger Clemens (1997) Blue Jays
Rube Waddell (1904) Athletics
Ed Cicotte (1917) White Sox
Cy Young (1903) Red Sox
Zack Greinke (2009) Royals
Ron Guidry (L) (1978) Yankees
Dennis Eckersley (1990) Athletics
Mariano Rivera (2008) Yankees
Fernando Rodney (2012) Rays