It's an interesting look at it, but I gotta say that some teams just have bad QBs, like the Lions. Kitna is like 32 and he just isn't any good.
Buffalo (Losman) - Flashing potential
Miami (Green) - Solid but old
Pats (Brady) - One of the greats
Jets (Pennington) - Good, but injury concerns
Balt (McNair) - Good but injury concerns
Browns (Frye/Quinn) - Poor vet, high-rated rookie
Bengals (Palmer) - Great young QB
Steelers (awfulberger) - Solid young QB
Texans (Schaub) - Flashes of potential
Colts (Manning) - One of the greats
Jags (Leftwich/Garrard) - Poor QB
Titans (Young) - Flashes of potential
Broncos (Cutler) - Flashes of potential
Chiefs (Huard) - Unknown vet, did well last year though
Raiders (Russell) - High-rated rookie
Chargers (Rivers) - Flashes of lots of potential
Cowboys (Romo) - Discussed ad nausem, flashed potential
Eagles (McNabb) - Good QB, injury concerns
Giants (Manning) - Borderline QB, consistency issues
Commanders (Campbell) - Flashed potential
Chicago (Grossman) - Flashes of potential, serious consistency issues
Detriot (Kitna) - Poor vet QB
GB (Farve) - Great QB way past his time
Minnesota (Tavarius) - Unknown
ATL (Vick) - Has the tools, consistency issues
Carolina (Delhomme) - Solid vet QB, consistency issues
NO (Brees) - Great QB
Tampa Bay (Garcia) - Solid QB that's getting old
Cardinals (Leinart) - Flashes potential
Rams (Bulger) - Great QB
49ers (Smith) - Flashes potential
Seahawks (Hasslebeck) - Good QB
Anyways, discounting poor QBs, ones with injury concerns, consistency issues and those getting old, you have 16 QBs that are good now or have potential. 17 if you include Brady Quinn, but I didn't since it would seem absurd since you passed him on the draft. At that point, it's mostly preference.