Roberto Clemente and Jackie Robinson ... Branch Rickey is one of the most influential Americans, let alone GMs.

I'm reading Branch Rickey by Lee Lowenfish (page 482 of 598). Lowenfish isn't much of a writer, but the information on Rickey's career is interesting anyway. Besides integration, Rickey also was innovative in setting up a true farm system.

But if I owned a team, I'd want Harry Dalton as GM.

Rickey is the man who invented the farm system, destroyed the minor leagues as independent operators, and integrated the game. So, yeah.

The other guys I would single out would be Sandy Alderson and either Lee MacPhail or Paul Richards. Alderson for two reasons: he was a non-baseball guy, who demonstrated that such a person could run a MLB front office. And he's left his mark on a number of major league front offices.

And the whole Baltimore strain that started around 1960 is still important. Paul Richards was originally the GM and field manager - he stepped down from the front office and Lee MacPhail came over from the Yankees (hey - there's my George Weiss connection!) and took the GM duties. Harry Dalton gets started under MacPhail, and this leads to the Frank Cashen line (mostly in the NL), the Hank Peters line (centred on Cleveland) and John Schuerholz. And meanwhile Richards moves to Houston, and starts a thread of his own.

Just for the record, I personally voted for Rickey. Even as I was putting the poll together, I was thinking "As great as many of these guys were, there's only one serious candidate here."

And no, Billy Beane was not considered for the list. His astonishing self-PR aside -- and yes, he's been innovative -- if you want to vote for Beane, vote for Alderson!

Barrow and Rickey are the great originals, apart from the owner-operators, from Mack to Finley, and the field managers who made their own personnel decisions, from McGraw to Herzog.

Rickey leads directly to at the very least Buzzie Bavasi, Joe Brown, Larry MacPhail, and the Warren Giles line, and its the Giles line which spreads his influence to the AL through Gabe Paul.

But Barrow built the first several great Yankee teams, which is something in itself; he also leads directly to George Weiss and Lee MacPhail. From MacPhail we get the Baltimore line, with Harry Dalton (from which we get John Schuerholz), Frank Cashen (taking this strain to the National League), and Hank Peters (from which comes John Hart and his apprentices)

I'd still vote for Rickey, but having traced that Baltimore strain back through the Yankee dynasties to Ed Barrow - I hate to see Barrow without even a single vote.

How little I know of Ed Barrow. The Toronto connection, for one thing.  The Honus Wagner "discovery", for another. 
Barrow was not a trailblazer like Branch Rickey (or Babe Ruth was as a player), but the man did know how to build a club.

from which comes John Hart

You write that like it's a good thing?

There's an interesting tibit into Branch Rickey and how he did things buried in this article on Ryan Howard. Do organizations still try things like this today?

http://www.philly.com/philly/sports/phillies/20080513_Bill_Conlin__Suddenly_there_are_more_experts_than_strikeouts_in_Ryan_Howard_s_slump.html