Every revolver is different and we can only speak in generalities, but the Python is going to give you a smoother action and most likely better accuracy.
Both revolvers are big and durable. The Python has a poor grip configuration and a small pawl, or hand, that wears quickly and throws the gun out of time more often than other magnums. The Trooper III is probably more durable, but was known for having sloppy tolerances. The Trooper Mark Vs were said to have been an enormous step up and that's the one I'd try to find. The grips and tolerances were greatly improved.
If I found a Python with a great bluing job (where the body and latch matched), I'd probably get it and just keep it in the safe. You can have the pawl hard chromed to increase its wear if you want to shoot it.
The Trooper III was not known for its great accuracy and generally lagged behind the Smiths and Rugers. You can check your individual gun by dropping a 125gr bullet into each of the chambers. If they drop through without stopping or sticking, the throats are oversized (this can happen with any .38/.357, though). My Rugers and Smith 686 all catch, but I saw a number of Trooper IIIs where the bullets just sailed on through.
I would love to have the Mark V in nickel. Can't afford the Python, but might trade for one. The bluing was astounding.