So, it's pretty clear from the other thread that the cage match is Brandon characters only. Let's get to discussing which sixteen characters get in.
I have a suggested bracket, but who do you think should go in? Here they are, not grouped by planet, since it's more fun to see everyone fight people from different planets.
1. Vin
2. Jasnah
3. Vasher
4. Raoden
5. Szeth
6. Alcatraz
7. Dalinar
8. Kaladin
9. Kelsier
10. Dilaf
11. The Lord Ruler
12. Sazed
13. TenSoon
14. Susebron
15. Sadeas
16. Marsh
My rationales:
Mistborn characters: Vin's advantages are obvious, being small, quick, and incredibly skilled. Kelsier has an edge of ruthlessness which will serve him well. Marsh has additional Inquisitor abilities which make him a force to be reckoned with. Sazed is all about planning and the strength of Feruchemy. It would be fascinating to see how he does. And TenSoon, because it shakes things up.
The Lord Ruler because I want to see how he will match up against other cosmere characters.
Way of Kings characters: Dalinar and Szeth are the easy choices. Jasnah is powerful and highly motivated. Sadeas for his well-timed betrayals, which would totally give him a huge advantage against someone more naive like Susebron. And Kaladin is awesome.
Elantris characters: Raoden, naturally. He has similar disadvantages as Sazed, but he deserves to be here. Dilaf for the same sort of class as Sadeas. (Sadeas vs. Dilaf would be amazing)
Warbreaker characters: Vasher because we need an Awakener. I want to see how he fares against a Mistborn or something. Susebron because he's surprisingly balanced--strong, but also naive.
Alcatraz because we need to remember Brandon writes more than cosmere novels, and because he'll sass you into submission.
In predicting some hesitance with the Lord Ruler, I don't think he's as overpowered as he might seem. Sure, if he goes against a Mistborn, he'll probably win, but him going against Szeth is much more interesting.
Of these sixteen, the one that I think is most likely to be replaced is Sadeas.