Mayweather's skills didn't match upto Calzaghes in the 20 by 20. I say this as Mayweather's number 1 fan too.
Speed, aggression and a good boxing IQ. Josh Taylor, to use a current example, has a style I think is a joy to watch.
Iron Chin. Most fighters have mandibles that are fragile, to one degree or another. To see a guy like Oliver McCall, George Chuvalo or Jake LaMotta absorb shots and keep coming is just awe-inspiring.
I enjoy the transformation of Clint Eastwood's character throughout the movie. In the beginning he reluctantly becomes a gunfighter but as the movie progresses you see how he slides down the slippery slope of wickedness to become the cold-blooded killer needed for the task. Morgan Freeman's reaction to the transformation is well played also. Richard Harris' character is colorful as is his sidekick. Gene Hackman's sheriff is pleasantly atypical of the role. All these actors and their characters effectively leave the viewer with a myriad of directions from which the movie expertly entertains. If you are expecting anything like Clint's "spaghetti westerns" you will be disappointed. If you are looking for an excellent story with characters that all have varying degrees of wickedness, you will be satisfied when its all said and done.
I like unorthodox fighting styles. I like when fighters create/try something new. Orthodox is boring. Personality wise, I like aggression and confidence.
Invite your opponent to hit you where he breaks his hand on your skull. Then the same with the other hand. Now he has no weapons.
Ring IQ has to be the most important thing unless you're like a one in a million puncher like George Foreman or Julian Jackson. You cant just take any great athlete and have him be a good fighter. You need to actually know what you're doing. How to set up your punches, when to throw them, when you block or use your head. You need to understand how to box. Or you could be Foreman and win Olympic gold 1 year after you start training. But unless you were born with freakish power you need to know how to fight. You can't just go in the ring and just start moving your hands and win. It doesn't work like that.