Expressing Thoughts

I think, the main points are ...
I see your point ... (but ...)
My understanding is ...
In my opinion ...
Why do you think so?
First, ... . Second, ...
You're right ...
I have a different opinion ...
Let's agree to that ...
I agree with you ...
I disagree with you ...
The bottom line is ... (the most important thing that you have to consider or accept; the essential point in a discussion, etc.: The bottom line is that we have to make a decision today.)