The web site "Hall of Stats" uses a sabermetric approach to evaluate the the Hall of Fame worthiness of every player. The methodology is based on an adjusted version of WAR (wins above replacement) and WAA (wins above average). Hall of Stats recently provided franchise pages, ranking all of a franchise's best players. Here is the link for the Astros' page.
Certainly there are no surprises at the top: Bagwell, Biggio, and Cedeno are the three elite players in Astros' history, with Bagwell holding an overwhelming lead at No. 1. Perhaps Roy Oswalt at No. 4, and ranking as the best pitcher in Astros' history, might surprise some people. I have argued in some previous posts that Oswalt is the all time best pitcher in Astros' history. It also might be surprising that Nolan Ryan is only No. 14 on the Astros' list. Of course, this brings up the point that the rankings are based only on the players' contribution to the Astros.
One thing that is noteworthy to me is the low rankings at the catcher position. Joe Ferguson, who played only a few years in Houston, is the top ranked catcher (followed closely by Ashby). Ferguson is the 60th ranked Astros' player, which tells you how weak the catching position has been over the years. I have followed the Astros for many years, and this is consistent with my observation that the team has experienced poor luck at the catcher position. The Astros always seem to be searching for that franchise quality catcher, but never succeed. They drafted catchers with the first round draft pick (Robbie Wine was the No. 6 overall pick in 1983), they traded significant players for catchers (Milt May, Ferguson, Ed Taubensee), and despite all of that, they never really had an elite catcher.
Any thoughts on the all time Astros team? All I can say is that is a helluva bench.