Throwing in my 2 cents worth
I own a 4" Python purchased new in the mid 60s, (Nickel) that became my duty weapon after using a 4" 66 for a couple years. With one glareing fault it was without a doubt the sweetest shooting revolver, out of the box, that I have ever come across. The trigger was typical Python with almost a 2 stage effect, the action was glass smooth and accuracy was excellent. I still have it and always will even though it has become a Safe Queen. The one fault I found with Pythons was the set of "Target" grips they came equipped with. My best description of them is Gorilla Grips, because you needed hands like a Gorilla to gain a firm controlling grip. Pachmyar grips solved that problem. In fairness, I have shot several newer Pythons and the Stainless ones just don't seem to have the quality of construction found in the older ones, but that is true of most all OTB revolvers today.
Trying to compare Pythons with 686s is like trying to compare Apples and Oranges. Other than the fact they are both 357s and both have full length underlugs they are words apart. My 686 shoots like a dream, is impervious to weather, strips down to its frame in a heartbeat for cleaning, and is less likely to shoot itself out of time, as Pythons are prone to do. took my Python apart for cleaning one time. The lockwork is considerably more complicated and delicate than that in the Smith. These statements are made with reference to the older model 686 with the firing pin on the hammer, the newer ones may be totally different.
Both revolvers are first class firearms. If I wanted one strictly for target shooting or PPC matches my choice would be the Python, but for a carry gun exposed to real life conditions, I'd opt for the 686 (older) every time.