Who cares about movie stuff?
What you're arguing is a difference between the crews, not the YC1s.
The Flying 6 were arrogant (hell, WW thought he was comparable to Lucci in any way) and ambitious men who had reached a very high position inside of a crew of strong monsters, three of which monsters are worth more than Katakuri, and they were aiming for the top, and always had the chance to become YC1 just by defeating or surpassing King, but as you said, no one surpassed King in that time, who actually remained invincible.
The Big Mom Pirates were vastly different. Katakuri was cool and strong, the strongest of the crew (below Big Mom obviously), but the whole crew composition, motivations and the links between them were different, you could actually see healthy sibling admiration for Katakuri.
King is, no matter how you look at it (featwise or portrayal wise) stronger than Katakuri.
Now, about what this thread is about, it's more subjective: whose design is cooler? You like Kata's design better? Good for you.