If you do not mind paying a higher fee for the potential of higher returns, mutual funds can be beneficial.
They can also be bought without trading commissions and allow you to automate specific transactions. For example, you can set automatic investments and withdrawals in and out of your account based on your preferences.
However, some mutual funds have a penalty if you sell your shares too early and they tend to be less tax efficient than ETFs as they attract more capital gains tax.
If cost and tax efficiency are important to you - ETFs are more cost-effective and have higher liquidity. They are also suitable if you prefer control over your trade price if you want to take advantage of market fluctuations.
However, ETFs have implicit and explicit costs. The operating expense ratio and trading commission expenses will be disclosed, but you must pay attention to the implicit costs like bid/ask spread and premium/discount to NAV.
The bid/ask spread is built into the market price and paid on each sale. So, the more frequently you trade, the more relevant this cost becomes. Realising small gains or losses from potential changes in discounts and premiums also makes you aware of the risks involved.
ETFs also generally provide lower returns than other types of mutual funds due to how they operate. Therefore, ETFs have a lower tax liability.