Ooh, interesting concept. The Goa'uld are dependent on the sarcophagus, though, right, so that's kind of Kandrona equivalent? The Yeerks seem slightly better at using human intelligence, too - fewer of the Pete's Evil Overlord List type of mistakes. Fighting the Goa'uld seems easier. And you can get the whole of the rest of the human race to join you in resisting, whereas more people will not recognise the Yeerks as a threat, due to their method of taking over.