I think john killing de Santa is more satisfying to see because de Santa murdered innocent people and a family so killing him made me feel like a hero

I'd like to say having John kill De Santa is more satisfying, but with hindsight letting the rebels do it feels more in line with John learning from Arthur and to a lesser extent Dutch that revenge is a fools game.

It looks badass when you walk away and look at him, plus John does not care about “stupid kid stuff and respect” as Johnny klebitz once said

I chose rebels because as john himself puts it "he's barley worth a bullet"