I also bought a 686 Plus. 4 inch barrel. The grandkids and I were putting a lot of rounds through my Python, so I decided to buy a 686 to take all that abuse. I really like the 686. Versus the Python, I like the 686 grip a bit better, and the newer sights. The Python has the better hammer and trigger pull (just my opinion) and is prettier. So, I had a gunsmith smooth out the 686 single action trigger pull, and it’s as good as the Python now, though the Python has the better double action - better in that it’s longer and stacks up predictably just before it breaks. The 686, to me, so far, has a more abrupt DA break, so I suppose it’ll take some getting used to.
If I had one shot, single action, at 20 yards, for all the money, I really don’t know which one to grab. Probably the 686, due to the better sights.