Large pots have several advantages over grow bags.
They can be moved easily.
Great for bush varieties.
Plants can trail over the side without reaching the ground.
It is more difficult for slugs to hide.
It is easier to plant a support in a deep pot than a grow bag.
Pots can be blown over by the wind.
It is more expensive to buy pots than grow bags.
Adding sand to the compost will improve drainage and make the pot heavier and therefore less likely to be blown over on a windy day. You could also put a large stone or brick at the bottom.
Gravel, stones or even polystyrene packing at the bottom of large pots help drainage.
Add perlite, vermiculite or water retaining gel to the compost to help retain moisture and prevent compost from drying-out too quickly.