Agreeing
I agree
I do.
I agree with you 100 percent.
I couldn’t agree with you more.
That’s so true.
That’s for sure.
That’s exactly how I feel.
I feel the same way.
You have a good point there.
I was just going to say that.
I had that same idea.
Exactly.
You’re absolutely right,
Absolutely
I’m afraid I agree with Janel.
I have to side with Willy on this one.
No doubt about it.
You nailed it on the head.
Neither do I
I suppose so.
I guess so. (is a weak agreement)
Disagreeing
I disagree.
I don’t.
I don’t think so.
I’m afraid I disagree.
I beg to differ.
Not necessarily.
That’s not always true.
That’s not always the case.
No. I’m not so sure about that.
No way. (strong/informal)
I’d say the exact opposite.
I totally disagree.