Digital downloads. There are more sales for digital downloads than for physical copies and the sales are bigger. With physical copies, you can only go down to a certain price, because the disk and the disk case have a manufacturing cost which needs to be covered. With digital downloads, the price can go as low as 1 dollar.
digital is great but there's really not enough space on the hard drive to hold many games. Even if you get 2tb it will eventually just fill up.
Physical copy is still the best way to go BUT it depends. Some games are just better off buying digital, they can be a lot cheaper. Id only go digital if the price is really low or if its a game that Ill always want on my console