Toss-up between Scully and Keith Jackson.
Phil Rizzuto (RIP) was a great guy, and was amusing to listen to. But he shouldn't be on the list.
Howard Cosell (#5) is the most overrated sportscaster of all time. The schmuck knew next to nothing about sports. Any sport. He shouldn't be anywhere near that list.
And Bil Walton (#39)? Hoooorrrrible selection.