I'm going with KS and Yair. I was extremely impressed with how easily KS was able to get back up to his feet (twice) in his last fight. Tavares is one of the better grapplers in the division and very physically imposing. Obviously, his striking is every bit as good as advertised. He's very fluid, very accurate and utilizes feints expertly. Yair is a unique physical talent, and I believe he's just scratching the surface. If I had to pick just one, for now, I'd probably slightly lean towards KS.
Ishihara intrigues me as well. His striking is pretty devastating. It's more than just the straight left, too; he was destroying Erosa with inside leg kicks and had Hirota limping out of the cage. Training at TAM will go a long way to help him round out his overall MMA game.