It's a matter of opinion.

Meaning

There's no right or wrong answer, it's subjective.

Examples

• John: Is pineapple on pizza acceptable?
• Alice: <b>It's a matter of opinion</b>. Some people love it, others hate it.
• John: I guess you're right. <b>It's a matter of opinion</b>, really.
• Alice: Exactly! There's no definitive answer.