Some of the guys below deserve to be in the discussion but many do not.
A list of coaches that are in the top 50 of the most regular season wins all-time, but no championships:
200 - Marty Schottenheimer
190 - Dan Reeves
186 - Chuck Knox
158 - Bud Grant
143 - Marv Levy
142 - Jeff Fisher
125 - Jim Mora
118 - Andy Reid
116 - George Allen
113 - Dennis Green
111 - Don Corryell
99 -- Norv Turner
87 -- Ted Marchibroda
87 -- Jack Pardee
84 -- Sam Wyche
82 -- Bum Phillips
82 -- Wade Phillips
82 -- Dave Wanstedt
Coaches with at least five playoff wins but no championships:
11 - Dan Reeves
11 - Marv Levy
10 - Bud Grant
10 - Andy Reid
7 -- Chuck Knox
5 -- Marty Schottenheimer
5 -- Jeff Fisher
5 -- John Fox
Coaches with a career winning percentage over .600 that coached at least 50 games, and no championships:
.712 - George Allen (1966-1977)
.694 - Tommy Hughitt (1920-1924)
.654 - Roy Andrews (1924-1931)
.646 - Paddy Driscoll (1920-1957)
.645 - Red Miller (1977-1980)
.624 - Mike Martz (2000-2005)
.622 - Bud Grant (1967-1985)
.618 - Andy Reid (1999-2010)
.613 - Marty Shottenheimer (1984-2006)
Coaches with the most years in the playoffs but no championships:
13 - Marty Shottenheimer
12 - Bud Grant
11 - Chuck Knox
9 -- Andy Reid
9 -- Dan Reeves
8 -- Marv Levy
8 -- Dennis Green
7 -- George Allen
6 -- Don Coryell
6 -- Jeff Fisher
6 -- Jim Mora
6 -- John Robinson
5 -- Wade Phillips
5 -- Bobby Ross
5 -- Jack Pardee