Monthly returns aren't automatically "better" than annual ones.
Key points
If you need a regular income for expenses, monthly returns might be more suitable.
If you don't need the cash and can reinvest the returns, compare the total actual return over the period.
Most importantly, compare products with the same duration and amount to see if the rate of return changes with the frequency of withdrawals.
The figures, fees and limits in this answer vary by bank and change over time — confirm them with your bank or the official source before acting.