On this site, you’ll likely hear that Kawasakis are better, on a Deere site they’ll say Deeres are better. In my opinion, they are both great sleds. If you compare the Invader to a 80-84 Liquifire, they both will have their positive and negatives…. For example the Liquifire handles better, while the Invader does better in the deeper snow (longer track). The later model Liquifire was tuned better, with a better design head, better clutches, and better ignition system. While the 81 Invaders vari-ride suspension had a superior ride. And of course there’s the looks aspect, which is subjective, but of course I think the Invader is far better looking.
Kawasaki also had better offerings in the later years, John Deere didn’t have comparable models to the LTDs and the Interceptor.