It really depends on what you want from a pet. If you want a pet that's independent, calmer, and chill get a cat. If you want a pet that may be outgoing, active and attention seeking, go for a dog. This is 100% rule of thumb tho, my old dog was not friendly with all people and was very lazy, so maybe she behaved more like a cat.
Right now for me, I'd vote... Neither, if I were living on my own right now. I generally work longer days into the evenings so if it were just me I'd feel bad I wouldn't have the time to spend with a cat or dog all day. That's why I have lizards
Reptiles, while they
can like attention and being handled, don't nessicarily
need it as much as cats or dogs do. Some actually prefer to not be handled or are mainly display animals as they are very fragile. We have two dogs as family pets and there's five people here in and out so they are rarely left alone. But the lizards are completely my responsibility, and they're good for me being a college student who works a lot.