As of the 2008 season, that would be the Cowboys. The Cowboys have won 8 NFC championships and 5 Super Bowls.
The Raiders have won 1 AFL championship, 4 AFC championships, and 3 Super Bowls.
The Cowboys have won more Superbowls (5 versus 1), but the Bears have won more NFL championships overall (9 versus 5). 8 of the Bears 9 championships were in the pre-Superbowl era - all of the Cowboys championships have been in the Superbowl era.
The Packers have won more overall NFL championships (13), but the Cowboys have won more Super Bowls (five to four).
The Cowboys have won 8 NFC Championships.
the raiders have won 3 superbowl championships
The Dallas Cowboys have participated in and won more Super Bowls than the Oakland Raiders. The Cowboys won in (1971, 1977, 1992, 1993 & 1995) lost in ( 1970, 1975 & 1978). The Raiders won in (1976, 1980 & 1983) lost in (1967 & 2002).
The Oakland Raiders/Los Angeles Raiders have won 3 Super Bowls.
The Cowboys won NFL championships in 1971, 1977, 1992, 1993 and 1995.
The Pittsburgh Steelers have won an unprecedented six Super Bowl championships. The Dallas Cowboys are in second place, tied with the San Francisco 49ers at five.