Best smartphone on sprint (now or in the future)?

I know Sprint doesn't have the best in anything, coverage or speed, but it balances those, and has a great price. What phone that Sprint will sell in the next five or six months (rumors included) is the best? Or what phone from other carriers accompanied with an explanation as to why they arebetter. A hardware keyboard is almost certainly required. If not, an explanation why the software keyboard is good enough would be helpful. Android and 4G ARE required. Specs like qHD and dual core processor are needed too. Battery is of top concern. The price of the actual subsidized phone doesn't matter that much. I have an Epic 4G, but I would like better hardware. Please be very specific and explain why. The keyboard and Battery are in the forefront of this decision. The top-of-the-line hardware should just be default.