If I was voting I'd probably vote for Whitaker, who has the highest career WAR of any of those considered, and Ted Simmons. Simmons had 50.3 WAR in his career, 10th all time among catchers, and a higher score than several catchers already in the HOF. I'd be tempted to also vote forTommy John and Dwight Evans.
Incidentally, of the players under consideration, the players with a the lowest career WAR are Parker and Garvey.