I have a Colt Python. I also have a few other revolvers. However, I am yet to find a better double action pull than that of a Python's. I think it is the finest out there and it will increase in value as Colt's snake series is now thing of a better past. As for SW or Ruger they might be good for duty sidearms, but dont compare to Python for collector's value in the long run.
I would say go for a Python, and then down the road add 686 (or any other new SW since they are still made) and a Ruger GP100 or SRH in .44 Magnum.