I've always adored both. And I've always had both as pets, at the same time. To me cats are lovable as*holes haha, but really independent, doing their thing, living their life. They are such goofballs, adorable, loving balls of fur, but I've rarely had a loyal cat. Since I was a kid I think I've had 6 different cats, and only one of them was really loyal. I used to live with my dad in a big house with a big yard, we used to always let our cats do whatever they wanted, and go outside whenever they pleased. However all of them left at some point - some we didn't see for months, some for years, some just never returned and lived with neighbours instead. My dad used to say they "change houses". But of course for people having only indoor cats, that's not the same.
Dogs however are really loyal I feel compared to cats, in nature. Dogs are your companion for life. They are sweet, and would do anything to make you happy. They never get enough of you. Right now I live on my own, and I just adopted a mini doxie, she's almost 6 months and it's the first time in my life I've not had a cat at the same time as a dog. I love her to bits. But, whenever I'll be able to, I'll also adopt a cat! (my apartment accepts dogs but not cats... how logic is that?)
Both are really different but they are, to me, the perfect balance. Their differences are what makes them so great. And I know whenever I'll get the chance, I'll adopt a cat because right now, even though I adore my puppy Fauna, I feel like there's something missing.