For everyday carry I suggest single belt, that goes through pant’s loops.
Inner velcro with outer belt is great for practice and classes. It’s very convenient.
Which one you want to use depends how much you would like your firearm to be concealed or close to your body.
If you decide to use single belt - be sure the material is sturdy and stiff enough to handle holster with firearm and the pressure you put on it during draw stroke. Don’t use “regular” leather belt.
For belt recommendation check few threads we already had at this Community.