Others ways to agree and disagree:
I agree/disagree with you.
You are right.
You are correct
I agree with you 100 percent.
I couldn't agree with you more.
That's so true.
That's for sure.
Sure.
(slang) Tell me about it!
Absolutely.
That's exactly how I feel.
Exactly.
I have to side with Dad on this one.
No doubt about it.
You have a point there.
I was just going to say that.