Lets Compare:
ASTROS:
Roger Clemens- 11-6 1.56 ERA
Roy Oswalt- 15-8 2.68 ERA
Andy Pettite-11-9 2.67
METS:
Pedro Martinez 13-5 2.77 ERA
Tom Glavine 10-10 4.10
Kris Benson 9-5 3.89 ERA
Victor Zambrano 7-10 4.07 ERA
You can not go by the records but even if you did the Astros starting pitchers have a better record. The Astros ERA is exceptional compared to the Mets. The Astros also have definetly a better bullpen then the Mets.
Jae Seo, in my opinion is a fluke and will not show up in the playoffs, Steve Trachsel is coming off back surgery and you don't know what he is going to give you.
Although, the Mets may have a better lineup, pitching beats hitting, and the Astros need to score 2-3 Runs a game to win.
Astros > Mets