Is it better to invest or pay debts?

For many PF blogs out there, the first answer that you would get if this is the question asked is to pay off the debts.

But the answer actually depends on your current financial situation.

First of all, list down all the debts that you have. Credit cards, hire purchase, mortgage, personal loans, student loans, etc. Next, find out what is the interest rate for each of these debts. 

For me, my current interest rates are as follow:

Credit cards - 15%

Mortgage - 3.85%

Note: I am paying off all my credit cards outstanding at the end of the month. So, I don't have to pay for the interest charge to my outstanding credit cards.

Looking at the above interest rate, I would choose to invest if I can be sure that my annual return of the investment is higher than the interest rate for the debts. But that is impossible to guarantee that my investment returns would be higher than 15%. Thus, I would choose to pay off my debts first.

But in another scenario, if I do not have the credit card debts but only the mortgage, I would definitely invest if I can find an investment that has proven to give me at least a 5% return. That way, I would be able to cover the interest of the mortgage plus earning a bit if passive income for myself.

Also, there are people that would choose to clear off the debts first just because they cannot accept the fact that they are having debts. For some, debts are totally unacceptable.

Which one would you choose?