Joe Namath never played for the San Francisco 49ers. He spent most of his career with the New York Jets before playing for the L.A. Rams.
He was not the greatest quarterback to play. He had some very good seasons in the old American Football League, but the final eight years of his career were less than stellar. He was frequently hurt and rarely played full seasons.
Several quarterbacks of his era were better. That would include Johnny Unitas, Bart Starr, Roger Staubach, and Terry Bradshaw. Fran Tarkenton, Ken Stabler, Ken Anderson, and Bob Griese also belong in the conversation. That does not begin to address more recent quarterbacks.