Hayward and Roy gets my vote. My reasoning is with Plante and Dryden the backup really didn't play a big roll, but in Hayward's case there were many times that he would play 2 in a row or 3 out of 4 when Roy was in a funk, so.....
Theodore and Garon has the making to win this title, if they stay together for a few more years and Garon can take his game up a little.
My vote goes to Roy/Hayward even though Roy was still shaky at times in the early years. Hayward was the best backup we've ever had imo. Larocque was good, but he hardly ever played and only fully developed when he left Montreal, though his career didn't last too long after that.
Vachon was still young and shaky when he left Montreal. Plante was young when McNeil was the other goalie in Montreal, but I don't think he had a backup after that, he was the only goalie.