It's not even to put down Luffy and his achievements to say that he currently doesn't have anything on Loki.
99 percent of the time, the arc villains acknowledges Luffy first. Imu, who was literally owned and seething about Luffy's parallel, or whatever, would be a great candidate to follow the pattern. But Oda had Imu huffing and puffing, warning his subordinates to stay away from the "Monster that Lurks in Elbaf"