I have done lots of research on tires of late as I need a new set. I have the AMG43 with 21" wheels...rides rough by the way but looks nice, I have a 20" winter set that is more comfortable (Michelin Alpine and love them). The Michelin Pilot Sport PS4 SUV rated very high for purely summer tires as did the Pirelli P zero PZ4, although they do not last as long as the Michelins and ride a bit harder. The Continental's that our vehicle came with are hard as nails and will not go back to them. Good luck.
I'm not a fan of the Continental tires that came with my 2019 GLC300. My SUV just turned 14K miles, and I see that the tread is already worn down. I can understand it if I do a lot of hard driving and stopping, but I don't. I don't know what the tire life is supposed to be, but I think it's a bit ridiculous that it's already worn down this early. My next tires will definitely be Michellin. We have that on our Minivan.
I, too, have a 2018 GLC, I have Scorpion run flat tires, and love them. The ride is smooth, I did have a puncture and true to the name I was able to go about 50 miles further, my son fixed the tire, and it is still going strong 2 months later. I have just ordered a second set of the same tire as at 35,000 miles I am seeing some wear.