For those of you who would like to know why Joker won. (Full credit goes to Jokes/Daniel. Not me)
Stats reason of winning: Joker and Jeff both pose roughly the same strength, speed, stamina and durability. Also both seem to be immune to pain so where people think Jeff's wild murderous rage gave him a advantage you were wrong. While Jeff is durable and crazy, Jokers craziness is a whole other level. Joker would kill himself to kill Jeff.
Intellect: Joker wins this by a landslide despite being insane. Joker has a genius level intellect, he's even outsmarted batman a couple of times so while Jeff had the rage, Joker was out smarting him and out strategizing him.
Weaponry: Joker takes this one! Also Joker has a unknown amount of weapons on him at all times, he even at times has bazookas hidden in his coat. While Jeff had 2 knives, Joker had everything else and then some. So his weapons would overwhelm Jeff.
Fighting skill: While both are street brawlers, Joker has had tons of more fighting experience than Jeff. Joker has even held his own against batman for awhile, he also beat Wonder Woman in a fight and she's trained by the god of war ares himself. While Jeff has never really fought hand to hand and mostly uses weapons and fights humans mostly except slenderman, but still Joker has fought the justice league.
Healing: Jeff has better healing than Joker and hasn't died yet, but Jeff has died for a short while before coming back, so even if Jeff is somehow immortal his healing takes time. So Joker wins because while Jeff has that killing rage Joker has fighting experience, intellect, strategy, and better weapons on his side so Jeff's healing really wouldn't matter because if Joker had explosives or a boozaka Jeff would be screwed.
Even those who defend Jeff wouldn't lose, It would be a tie because there is no way Jeff would kill Joker and walk away so either Joker would win or they would kill each other simple as that.