He seems to be stronger

I think they're both on the same level ^^

Honestly, I think a samurai would win

Hm...I'd prefer it to be a draw. Taking their teen selves into consideration, I believe Yamamoto would win, due to his ability to think calmly and stay focused. However, when they grow older, Gokudera becomes a lot less hot-tempered, so he might win then. ^^ If only he could keep himself in check, his power and brains would become make him a powerful opponent.