Marsh is an Inquisitor with access to most of the metals and a lot of the most dangerous compounding. That said, he's a gnat to Kelsier or the Lord Ruler. He might be able to keep up with them in reaction speed, but nicrosil compounding means that he's still a fair bit weaker than either of their boosted A-pewter, and also won't be able to move quite as fast since he won't be as durable. He might be able to get in a lucky shot with duralumin though.
I think it's a fair bet to assume TLR did not have access to nicrosil or chromium, even if he did have knowledge of them. It would be really hard to produce either with pre-industrial technology. But even if he did, he would be at a disadvantage when facing Marsh or Kelsier, who know his weakness and how to exploit it.
Kelsier is a Fullborn, and so is equal to The Lord Ruler in power, though he only has 300ish years of experience to the Lord Ruler's 1000. Despite this disadvantage, Kelsier is possibly even more dangerous than the Lord Ruler is, since, as a Cognitive shadow, he may not need atium metalminds to extend his life, and thus would not have an easily exploitable weakness. In any case, both Wax and Marasi were able to push on metals embedded in peoples' bodies by increasing their level of Investiture with F-nicrosil. Kelsier would be able to do the same to TLR's metalminds, even if he swallowed them. Kelsier has easy access to all sixteen metals and can leech the investiture out of any opponent he faces (though he hardly needs to!). Unlike TLR, his access to nicrosil is confirmed and he will definitely be able to abuse Nicrosil and Chromium (either of which would probably guarantee a win if the Lord Ruler doesn't have access to them)
If the mists are in play, Vin could be as dangerous as the others above, but she still probably does not have the hax to beat Kelsier, who has access to compounding, as well as Allomancy on mist-powered Vin's level, though he would have to expend metals to use it.
Zane would die fairly quickly to most of the power players, including the Heralds and Elantrians.
Vasher is out of his league, no? I doubt he survives the massacre at the beginning, even with his enhancements and skill.
Everyone dies except for Kelsier and maybe Jasnah by escape to the Cognitive Realm
TL;DR: Kelsier wins easily, with Rashek being his only serious opponent. Even then it's not really close, since Kelsier has infinite luck and Allomantic potency to go along with functionally infinite healing, speed, and strength. Plus you can't kill him by pushing on his bracelets.