Here's a list of different ways to say "I disagree", useful for test preparation and improving your speaking skill.

How to disagree in English-phrases

I'm not sure that I agree with those findings.

(this is formal expression) I beg to differ. You did a really nice job and deserved the promotion

You think that painting is beautiful? That's not how I see it.

I understand what you're saying, but I have a different perspective on that.

I’d say the exact opposite—more training is undoubtedly what this team needs!

All cats hate water.
Not necessarily. Most do, but mine loves to swim.

I can’t see eye-to-eye with you on that. I think the best approach is to remain as available as possible.

I can’t see eye-to-eye with you on that.