On Saboady, when Kuma scattered the Straw Hats, he had a definite plan beyond just "best for them" for at least half the crew:
Zoro: Kuma probably had great respect for Zoro, seeing as he took all of his captain's pain and survived. So he sent him to Mihawk, who probably was the only swordsman stronger than him.
Sanji: while Kuma didn't like Sanji as much as Zoro, he still respected him for trying to take his captain's pain. So he sends Sanji to the land of his close ally Ivankov. (he probably had no idea about Sanji's attitude about women and okama.)
Robin: Kuma knew of her powerful abilities and knowledge, so he sent her close to where the Revolution was at.
Franky: Kuma definitely sent Franky to Vegapunk's island, either so that Franky could toughen himself up or so Franky could restore some of Kuma's free will.
Nami: Since Weatheria is a moving sky island, it's possible that Kuma had an entirely different plan for her.
Linking off of Nami; Brook, Usopp, and Chopper were all sent in places where they could easily be killed, yet had the chance to become stronger. I'm guessing that Kuma didn't know/care enough about these four to send them anyway specifically, and just gave them a 50% chance to either die or become stronger.
And finally for Luffy. Why in all god's name would Kuma send Luffy to an island that specifically kills all men found there? Was Kuma hoping that Luffy would be strong enough to survive? Or did he receive orders from Dragon to eliminate any pretenders to the position of Revolution leadership (or weak points for Dragon to be manipulated) and so sent Luffy off to a place where he'd most certainly die.
So in conclusion:
Kuma helps/uses: Zoro, Sanji, Robin, and Franky
Kuma doesn't really care about: Nami, Usopp, Chopper, and Brook
Kuma tries to eliminate: Luffy
Sorry if this is a bit messy, I'm quite tired.