I hear that generac is good. Kohler is the bee’s knees for permanently installed ng units.
Honda makes excellent portable, gasoline units, very pricey though compared to generac et al.
Can’t go wrong with a Generac. Sure its a Chevy compared to Mercedes, but the cost is good and it runs solid. Mine never fails to start had it 15 years. 6500KW. Fuel is propane. Had to do a conversion kit back in that day. Connects to a 6 port transfer switch. Runs the whole house. Check Norwall Power Systems to browse for hours.