Here's the list, from 1992-2006 (inclusive), with each team's number of sub-.500 seasons:
Yankees - 1
Braves - 1
Astros - 1
Dodgers - 3
Red Sox - 4
Cards - 4
White Sox - 4
Dbacks - 4
Indians - 6
Athletics - 6
Giants - 6
Angels - 7
Mariners - 7
Blue Jays - 8
Twins - 8
Mets - 8
Nationals/Expos - 8
Phillies - 9
DRays - 9
Reds - 9
Rangers - 9
Cubs - 9
Padres - 9
Marlins - 10
Orioles - 10
Rockies - 10
Royals - 12
Tigers - 13
Brewers - 13 (AL 5, NL 8 )
Pirates - 14
The Astros will pick up #2 this year, and the Braves might (only two games over right now), potentially leaving the Yankees alone in "first." Yes, 1992-2006 is a somewhat random collection of seasons, but it does illustrate the Astros' continued success of late. And if you cut off 1992, and just cover the years Drayton's been in charge, the top 10 doesn't change.