What cryptocurrency do you think is best for selling digital products?
since this is a digital product, i would say it doesn't matter which coin you accept, it will depend on what you will do with those coins after.
if you want to get USD or local currency after, stablecoins are the best, so you don't have to deal with market volatility.
if you want to add them to your stash to hold, BTC or ETH would be the better option.
me personally, i would enable all top coins on my store, and let the buyer pay with whatever coin they want, you would also get more sales doing that, and you can just exchange them to stablecoins.