Let's start with Sartana, my favourite SW character together with Django.
A distinction should be made between those films in which the look of Sartana is in some way maintained, albeit to a minimum extent, and those films in which apart from the name the main character has nothing to do with the original.
Sartana's Here... Trade Your Pistol for a Coffin, Sartana Does Not Forgive, Sartana in the Valley of Death and Django Defies Sartana are placed in the first category, and here in my opinion George Hilton and George Martin are without a doubt the best incarnations, followed by Giorgio Ardisson (the first moustached Sartana!) and William Berger.
As for the second category, not counting Sartana Kills Them All with Garko himself, to my way of thinking the most interesting alternate Sartana is certainly the one played by Jeff Cameron in two Fidani movies, inelegant and miles away from the original. Fabio Testi is colourless and uncharismatic in One Damned Day at Dawn and Franco Borelli/Chet Davis far more convincing as Stranger in Dead Men Don't Make Shadows, while as we all know the two films with Alberto Dell'Acqua are hard to compare SW comedies.