I'm fine with your opinion.
Here's the argument for Branch:
Had Branch Rickey retired from baseball in 1942, before he ran the Dodgers, before he signed Jackie Robinson, his record as a general manager would still be enough to warrant consideration as the greatest GM in the game’s history. By that time he had already built one of history’s best organizations, winning six pennants and four World Series while completely revising baseball player development and instruction and inventing the farm system model that is still in place nine decades later. When you add in his Brooklyn years, both the building of one of baseball’s best and most iconic teams and his historic and courageous act to integrate the game, it is a relatively easy call.
Branch Rickey first envisioned an organized “farm system” as a solution to the high cost of buying minor league players. A team could instead sign amateur players (for much less money) and then assume the cost of developing the players on teams under its control. Rickey became a legendary talent evaluator, able to make decisions quickly on players. Among other things, he valued speed and youth. No sentimentalist, he tried to trade players before they started to decline rather than after. With his huge farm system, he believed he could fill the holes created when he traded his veterans away.
From 1926 to 1946 the Cardinals won nine pennants and six World Series. Rickey did not have complete control of the club — Breadon hired and fired the managers, for example — and the relationship between the two men had become a bit strained by the early 1940s. When the Dodgers offered an ownership stake and more authority in October 1942, Rickey moved to Brooklyn. (Sound familiar?) Rickey could not do much with the war going on — all his players were in the service — but he worked on building his farm system to be ready. In 1943 alone the Dodgers signed Rex Barney, Duke Snider, Gil Hodges, and Ralph Branca. Over the next couple of years Brooklyn added Carl Erskine and Clem Labine, two other mainstays of Dodger teams to come.
The most important event of Rickey’s career, of course, was the signing of Jackie Robinson in October 1945. After losing a pennant playoff in 1946, the Dodgers won NL pennants in 1947 and 1949 and then lost in 1950 on the season’s final weekend. Unlike the prewar teams, by 1950 the Dodgers had several good players in their twenties and more on the way. In late 1950 Rickey began to sense that his position had weakened with his partners and decided to cash in his stake and take a job running the Pittsburgh Pirates. Walter O’Malley bought Rickey’s share and gained control of the club. The core of talent Rickey left behind won four more pennants and the 1955 World Series. The acolytes he left, including Buzzie Bavasi and Al Campanis, built on Rickey’s foundation to create and maintain baseball’s model organization for another four decades.