I have had both.
I think cats were easier, but personally I find that owning a dog has been more rewarding for me.
Is it easier to own a cat or dog? I think cat.
Cats are easier to own, but suck bigtime in all other ways.
Nasty bird-killing garden-pooping machines.
Also the last domestic pet in most of Europe to still carry fleas.
Hey, they are so bad that even people in the far East won't eat them!