The five Kage, definitely. I thought people will think the same, but obviously, they think otherwise, according to the poll. So, here's what I have to argument my beliefs:
1) Only Naruto can keep up with the Raikage, and Sasuke would spend a lot of chakra to defend, and Sakura and Kakashi would be burdens there.
2) The Tsuchikage is amazing on so many levels. Kekkei tota, people. It's almost impossible for me to imagine someone could beat him without taking serious damage. If it were to happen, it would have to be some awesome eye tech by Sasuke that we don't even know of yet. Naruto can dodge, and is busy with the Raikage. What about Sakura and Kakashi? Burdens, again.
3) Tsunade is on a whole other level to Sakura as a medical ninja. Regeneration and possibility to summon a healing slug to aid her friends. Again, advantage - 5 Kage.
4) The amazing Mizukage. Again, a kekkei genkai. And one that can mess up Sasuke's strongest defense only with one breath. Damn, she needs to brush some more.

5) Finally, the awesome Gaara. One of my favourite characters in the manga. Not a huge variety of abilities, but an incredible specialty in utilizing sand for many purposes. One that can reshape terrain in a blink of an eye. For him and the Tsuchikage, terrain or numbers are not important. They are, on their own, in a special abilities league. Tsuchi with power, and Gaara with brains.
Sorry if it came out long, I tried to keep it short, but it all got a a little messed up somewhere along the way.