This would actually be a good topic: Who are the greatest coaches to never win a Super Bowl?
Say what you want about Reid but he has a great record:
Career record 129-82-1 (Regular Season)
10-9 (Postseason)
139-91-1 (Overall)
Off the top of my head I'd say Chuck Knox, George Allen, Marv Levy, Marty Schottenheimer, and Reid have to be the best coaches to never win one.