Then there is no “best” charger. They all do the same thing—provide current. Electrically it’s very simple. But some cheaper manufacturers skimp innovates quality to get The price down. I’d stick with brand names that you recognize—Apple and Anker are the only two I buy.One that charges fast and safely
I have the single port version of that and it works great with my 2018 12.9 and XS Max (had to buy a USB-C to Lightning cable - surprise!). Wish I had this dual port version.