https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_...
Then sort by "Total Deliveries" Column.
You'll get a list of airlines that have taken delivery of the Max. (an inverse list)
Southwest 187 United Air 136 Ryanair 124 Alaska 63 American 55 Aeromexico 51 Flydubai 49 Air canada 40 Copa Airlines 26 Turkish Airlines 25 WestJet 23 Lion Air 22 Akasa Air 20 Norwegin Air 18 Air China 16 China Southern 16 China Eastern 14 Ethiopiean Airlines 13 SpiceJet 13 Singapore Airlines 10
etc.
A few years ago, I happened fly on Southwest flight on a brand spanking new 737 Max. The captain announced that it was the first "Revenue Flight" of the plane. That was exciting.