That may be true, but . . .
I may be wrong, but . . .
You might be right, but . . .
You have a good point, but . . .
You could say that, but . . .
Correct me if I’m wrong, but . . .
I don’t mean to be rude, but . . .
I hate to bring this up, but . . .
I don’t mean to be negative, but . . .
This may sound strange, but . . .