“Should I pay off debt or invest first?”

There's a genuine order of operations here, though the exact line moves depending on your situation.

First, almost always: contribute enough to capture your full employer match, if you have one. Turning down free money to pay down debt faster rarely wins the math, even against fairly high interest rates.

Second: high-interest debt — credit cards, and anything else in that range — is usually worth prioritizing aggressively after the match, because that interest rate is a guaranteed cost working against you every month, in a way market returns aren't guaranteed to beat.

Beyond that, it gets genuinely personal: a lower-rate loan (some auto loans, some student loans) sits in a grayer zone where either choice can be reasonable, and things like your emergency cushion and your stress tolerance matter as much as the interest-rate math. There isn't a universal answer past the match and the high-interest debt — that's exactly the kind of tradeoff worth talking through with someone who can see the whole picture, not just one rate.