For me, it's their personality. I've had many beautiful & handsome cats enter my life, and some have captured my heart in ways I never thought possible. Take my cat Nubey (who I had to put down a few years ago because he couldn't eat anymore) for example. When I found out my grandparents (who I lived with at the time) were going to get a black cat that was a lap cat who loved giving hugs & kisses, and loved being held who was pure black, I couldn't believe it. I remember the 4th or 5th day he was with me & my grandparents. I happened to be at the house, just minding my own business, watching TV, and then the cutest moment happened..... I can't remember what I was watching, but at some point, Nubey saw me, and he stopped at my feet, looked at me, and in just a split second, he jumped on my lap, settled in, and purred in my ear while looking at me as if to say "Hi Nathan! I'm Nubey! Pleased to meet you!", and then he nudged my face. I couldn't believe how sweet he was. Then, the next day, the first time he saw me, he literally jumped on his hind legs, put his front paws on my legs, and gave me a big black cat hug!!!!! I was shocked & delighted. He was quite a talkative cat, and one thing he absolutely loved being called was "Nubers"!!! (He also loved being called "Bubba" or "Buddy"!) He'd purr really loud when he was near me. He'd also "Bang" my chin by nudging it HARD with his nose. He was, in my view, THE PERFECT cat!!! He loved rubbing me on the face, and I loved that big tail of his bonking me on the face, or brushing my legs or face as he walked by.