You're absolutely right.
B1Completely correct.
I couldn't agree more.
B1I completely agree.
I think so too.
B1I agree with that.
I'm of the same opinion.
B1I hold the same view.
I totally agree.
B1I completely agree.
I disagree.
B1I do not agree.
I'm not so sure about that.
B1I have doubts.
I beg to differ.
B1I respectfully disagree.
I don't think so.
B1I disagree.
I'm afraid I disagree.
B1I disagree, politely.
On the contrary...
B1In contrast...
That's not quite right.
B1That is partially incorrect.
I'm not convinced.
B1I'm not persuaded.
I have my doubts.
B1I am uncertain or skeptical.
I'm not sure I agree.
B1I'm hesitant to agree.
That's debatable.
B1That is a matter of opinion.
I'd say...
B1I would suggest...
To my mind...
B1In my opinion...
Perhaps not.
B1Possibly not.
I'm not convinced that...
B1I don't believe that...
However...
B1Nevertheless...
I see your point.
B2I understand your argument.
That's a valid point.
B2Your argument is reasonable and well-founded.
I agree with you.
B2I share your opinion.