Hi fellow fan <3. Surprisingly not. I'll give you a short and long answer.
Short answer: everything

Long answer: I was mostly drawn to his character design and the art style, I mean look at it. It always seemed like such an expressive and well drawn/emotive show to me, just peep the El Tigre production art. Very fluid and action-y and original.. the designs, I love them so much.
His looks specifically, not sure where to start. I really like his voice and accent. Character voice is always a high factor for me. I like the fact he has freckles, they come off as adorable to me. And they're a great contrast to the badass scar on his face (Which is canonically self-inflicted when he was first testing out his powers.) Not very often seeing darker skinned characters with freckles as well. I enjoy how curly his hair is, that's also a nice change of pace. It makes me want to give him headpats. Then I guess I like how short he is and his proportions in general lmao
Personality? Well the fact he wants to be super macho and manly in and of itself. Especially when something contrasts that. It also gives me the impression he's fond of being control, especially in things such as age gaps or dominating villains or other people he'd get close to. But then on the opposite expectation, that also makes it better when he isn't in control or doesn't entirely consent, because he'd hate to feel weak or lose at anything. Or the fact he's easy to manipulate as much as he likes to manipulate people, or do things for money or valuables.

Tysm for the intriguing question <3