sabo shouldn't be here, yeah he may be working under dragon but it's too early to have him here
hmm he might be as strong as luffy now, seeing as he was ace's rival I can't see him beeing weaker than luffy when introduced again
marco is strong so that leaves kinemon and ryuma, since I'm not allowed to consider alive ryuma I'm going to vote for him
1. Marco. He was the right hand of Edward Newgate. He showed his strength during the War at Marineford and he is still one of the strongest leaders in New World even though he and his friends lost the war for WB's territory in New World to BB and his crew.
2. Kinemon. He should be the one who gets the second place in this group. He looks considerably stronger than Ryuma in his Zombie form and he can confortably take him with his flame style attacks.
Kinemon Vs. Ryuma now that would be an epic battle to see!
It would actually be a great fight to have in the manga (). I think both would actually sustain some injuries. Ryuma would definitely get a hit on Kinemon. He's very potent in the manner in which he attacks his opponents. He wouldn't make a silly mistake or error frequently anyway. Kinemon would probably get the better of him though. Two sword style and a funny/weird df ability as well which will some how aid him in the most unexpected way.
Marco will clearly go through. Followed by Kinemon.
Ryuma has a bad match-up as both of his opponents can perform flame-based attacks and thus he would be burnt quite easily and that's his real problem...
So even though he was a strong fighter, I doubt that he would put a serious fight against Kinemon, cause the guy seems considerably stronger even in terms of pure swordsmanship.
P.S. You should also take in consideration that I'm talking about zombie-Ryuma. Not at his best as a swordsman.