That's right.
(その通りだね)
You're right.
(あなたの言う通りだ)
You're absolutely right.
(全くあなたの言う通りだ)
I agree with you.
(あなたの意見に賛成です)
You've got a point.
(一理ありますね)
I was thinking the same thing.
(ちょうど今同じ事考えていました)
That's a good point.
(いい点をついてるね)
That makes sense. / That stands to reason.
(それは理にかなっていますね)
So do I. / So am I / Me, too.
(私も[同じ意見です])