IMO, Lions are better on the savanna than tigers are.

Reasons:

*Lions can run longer distances before getting tired and can run faster (up to 50mph), which is perfect for chasing down that nasty zebra or antelope that got away.

*Lions will work in groups to take down animals, I don't care how strong or agile your tiger is, tigers cannot grasp the concept of working with other tigers to come in at multiple angles and that reduces their chances of a successful hunt.

*Although tigers have more powerful jaws and stronger flank muscles, lions have more powerful forequarters, mainly to drag animals down to the ground more easily and in cases of crocodile attack at a local waterhole, to drag things out of the water more easily.

*Although both would be damn hard to see on the plains, the lion is just the right color to blend into grass.

*Tiger pelts are more valuable on the black market, thus the tiger would get shot by a poacher, making the lion the default winner.