If the gun is going to be a regular shooter then go stainless and don't look back. Parkerizing is a cheap, fairly durable and corrosion resistant (if kept well oiled) finish, but it is just a finish and is prone to scuffing, scratching, general marking up and, of course, holster wear (if you plan to use a holster). If the gun sees a lot of use, the Parkerizing will eventually need to be redone and, because it is a rough-ish finish, it typically starts to show signs of holster wear quicker than other finishes.
Stainless, on the other hand, is not a finish at all but rather is just the bare steel. It may get a little banged up over time, but never needs refinishing. Occasional buffing for noticeable scratches and dings is optional as you don't really see them unless you are looking very closely at the gun. Stainless is corrosion resistant as it is and, unlike finishes of any type, does not require any re-oiling or special attention to keep it's corrosion resistance.
On top of that, a SS 1911 just looks bad-ass. At least they look bad-ass to me!
YMMV
Good luck with your decision! It is a tough one for sure!
