A: I think honesty is the best policy.

Question

1. Me too.
2. Same here.
3. I have the same idea.
4. I agree with you.
5. I think so, too.
6. You can say that again.
7. That makes two of us.
(Are the responses all correct?)

Answer 1

All acceptable, however, number 4 is probably the best, with number 2 and 6 being the least best.