Thought experiment:
You are the GM of the All-Time All-Star team and get to pick your own personal five-man rotation for the Eternal Season. Consider mitigating factors -- type of pitcher, righty/lefty -- but don't worry about "salary" or "contract status." Important tie-breaker: all else being equal, pick your favorites. Only Major League pitchers are eligible for this team, so if you want Satchel, you get the wily vet, not the fireballing youngster. Oh, your bullpen consists of a variety of league-average clones, so get the guys who can go deep into games!
As they say in the TV commercial, who's in your five?
For me, it's three righties and two lefties ... Seaver, Koufax, Clemens, (Randy) Johnson and (Phil) Niekro -- no bullpen, gotta have a knuckleballer around. Hey, gotta have a knuckleballer around regardless! And as much as I'd like to make a case for personal favorite Tom Browning, the former 20-game-winning lefty doesn't bump Unit or Koufax.
Yes, yes, Lefty Grove was pretty good. Yes, yes, Walter might have been the better Johnson than Randy. Tough. That's MY rotation. What's yours?