hmm, hard to say. i like lots of animals for lots of different reasons. my favorite primate is the fat tailed dwarf lemur bc they're so darn cute and one of the few primates capable of hibernating (and it's even cooler that they do it in the tropics). naked mole rats are one of my favorite mammals bc they fucking ugly but can survive without oxygen for a whopping 18 minutes (that's longer than any other mammal!). i have embryos of the Venezuelan annual killifish tattooed on me because i study them for work, and when controlled for temperature they are THE most anoxia tolerant vertebrates we know of in the world. i also think echidnas are cool, but i like monotremes (egg laying mammals) in general because of how unique they are

In terms of favorite species, I'm a basic bean: Cats. I enjoy petting them, their purring sounds, I enjoy how they are independent.

But in terms of individual animal? It's weird. It's a dog I know, called Sam. Which is weird, because I'm afraid of dogs. But Sam is such a sweet heart that I just can't help it. He's very friendly and cuddly, but won't jump at you (and will match your energy within seconds). He barely barks (basically when he's found a big stick to play with), but he has proven that he would protect people when necessary. He's an absolute dumbass, but will come running when he senses you're not doing well (I once saw him cuddle someone who was crying).

So: Either cats, or one specific dog.