Mayans vs. Zulu
Both had jungle training, relatively similar weapons in sophistication, and were vicious warriors who loved to kill. It's crazy that South America was left out of last season entirely, considering its warrior history. Plus, I kind of have a crush on one of the Zulu expert guys and would like to see him back.

Incas vs. Spanish Conquistadors
Yes, we already know how this played out in real life, but if you don't count "Pizzaro's bullshit lies" as a weapon it might be a closer fight.

Spetsnaz vs. Sayeret Matkal (Israeli Special Forces)
I loved the Spetsnaz guys and was very impressed with their skills, but I really don't think anyone could beat the Sayeret Matkal. Even Batman does Krav Maga now, and it's because even fricking Batman wants to be like the Israeli special forces.

Julius Caesar vs. Alexander the Great
Just so people can stop saying they should do this fight. Personally, I don't really care about either of those guys' armies, but clearly I'm alone. Let's just get this obvious one over with.

Genghis Khan's Peeps vs. Attila the Hun's Huns
For the same reason as the above battle, even though these two have literally nothing to do with each other. But, people keep clamoring for it, so I'm sure they will do this fight eventually. I say Genghis takes it because he was smarter and has like 800 years of weaponry advancement on Attila, but Attila does have the crazy working for him, which can be an asset. In an unrelated matter, I've never noticed how adorable an army called the "Huns" is.

Hell's Angels vs. Crips
Hell yes! Harleys and low riders! They've done a little bit of this on Sons of Anarchy, and it's awesome every time. Only bummer would be if they had to blur out the experts' faces like they had to with that one IRA guy, but it would still be worth it.

Chinese Triads vs. Colombian Cartels
I really liked the battles last season between just flat-out criminals, and I've been intrigued with both these gangs since Lethal Weapon 4 and XXX, respectively. Triads for the win though, no question.

Fictional ones!
Debating how real warrior cultures would fight each other and who would be victorious based on things that can actually be scientifically tested is fun and all, but nothing would be more controversial than pitting fictional characters against other fictional characters. Literally nothing. You could have Osama Bin Laden biting the head off a bald eagle in a cage match and no one would be as upset about it as they would if you alleged that Han Solo would get his ass kicked by one of the chicks from She Spies. So don't do that one, show! You'll get in nerd trouble! Here are better ones:

Snake Plissken vs. John McClane
Chev Chelios vs. Mad Max
Sydney Bristow vs. James Bond
Jack Bristow vs. Keith Mars (that one hurts my heart!)
Chuck Norris vs. Jean-Claude Van Damme
Rambo vs. Dr. Owen Hunt
Terminators vs. Cylons
Orcs vs. Dwarfs
Napoleon vs. An ice cream sundae
Don Draper vs. Dick Whitman
Jack Bauer vs. Starbuck
Blade vs. Buffy
True Blood's Eric vs. Spike
Michael Weston vs. MacGyver
Dexter vs. Hannibal Lecter (fun!)

The possibilities are endless! Leave your dream fights in the comments below!