Credit Unions usually pay higher interest rates on your savings accounts or checking accounts you have with them.
Also credit unions will usually give you a lower interest rate as well on car loans, mortgages etc.
But the main disadvantages is that the credit unions usually have less branches where you can access your account from.
Regular banks usually have more than a few locations that you can deposit money into or withdraw money from if you need too.
The credit unions online banking is usually more poor than a traditional bank account as well.
If you want to earn higher interest on your savings account then a credit union would be the better option but if not then a traditional bank account would be your best option.
I used to bank with a credit union but found it wasn't worth it as they had less branches where I could access my money or deposit cash or checks.