If you define winning as surviving, I'd go with Eldrad... as he'd likely slip out as soon as he saw what was going on. The remaining three would probably deal each other mortal wounds. Eldrad wins by default
Abbadon... more like Failbaddon http://1d4chan.org/wiki/Abaddon I think that the only two last standing would be space marine and eldar... but I don't know who would win... I wish that the Lord of Macragge would crush the xeno with his powerfists!
"Despite the fact that they wanted to make a dude who was the magnetic and indomitable personality that managed to get Chaos to get its shit together 13 times, despite the fact he rewrote the book on evil after Horus went down, and despite the fact that he is the #1 threat to the Imperium at large" "However, he actually did conquer Cadia as per the results of the Eye Of Terror Campaign but then the imperial players threw a bitchfit saying it was a corporate conspiracy or that chaos somehow cheated (look at the actual campaign results). So Chaos controls most of Segmentum Obscurus and Pacificus (Night of 1000 rebellions) and Abaddon and his fleet are making their merry way to Segmentum Solar but will never get there because GW won't advance the storyline.*" Source: http://1d4chan.org/wiki/Abaddon
If Eldrad was not in the warp, then him, but giving the fact that he is still lost, most likely Magneus.
Another option: an Inquisitor calls down exterminatus on the planet and kills them all in a brutally efficient way.
