Garfield seems like an Se dominant; he's in no way Ne dominant, he doesn't seek novelty, new ideas, nor does he branch around various concepts. Instead he's a lazy ass hedonist, which seems evident of Se dom, probably ESTP. 7 or s9 should be somewhat accurate as well, although I'm not sure which fits him the best. Instinctual varient wise, I'm not sure, but sp sounds like it would make more sense.
John as an ESFJ could work I suppose. Enneagram 2w3 perahps? I mean isn't the guy constantly trying to date women and establish a relationship? Just seems to ring of the whole 'love and be loved' type of person, which would indicate 2. Instinctual varient, sx something. Anything other than sx first is . . . just stupid.
The only question about the 7 or 9 e-type dilemma would be: can a 7 go around acting like a 9? And do it all the time, without fail, the way Garfield does?
Here are the two options you've given for instinctual type 7 Sx:
"Sexual/Self-pres
The energy of the sexual instinct is, in some ways, at odds with the type Seven fixation. The Seven’s focus is future oriented and outward, away from the inner world, while the sexual variant is instinctual and dwells on the inner self as far as relationships and identity are concerned. This combination can make for a Seven that can be Four-like in many ways. They can have a flamboyant style and be very moody and intense. In relationships, there is often a push-pull quality. They are very attracted to the falling in love part. The buzz and high of that is very stimulating to them, almost drug-like for them. Their problems come when that buzz wears off. They want to recreate it again and again, but they also have a way of becoming attached and sometimes very dependent on their romantic partners. On the down side, they can be very clingy but don’t want at the same time to lose their freedom. When unhealthy, they can be very selfish in these relationships, things become one-sided in a way that favors the interests of the Seven.
The sexual/self-pres Seven’s addictive behavior with relationships can extend to other areas, like music, and performing in general. The rock star image and lifestyle can be attractive to the sexual Seven. Many rock stars are sexual Sevens the buzz they experience from music can be similar to what they experience in relationships. Creativity can also function as a release of frustration from the boredom.
Sexual/Social
This subtype has a lot of energy, crazy, intense energy and this energy is going to find a way to manifest. This subtype of Seven can have the biggest extremes in behavior and with material success in life. With the self-pres instinct last in the stacking they aren’t afraid of taking risks, so they sometimes become very successful, as in the case of rock stars, but they typically also take too many risks, look for too many easy ways out. With the self-pres least developed, they can become dependent on others to add a much needed stabilizing element to their busy hedonistic lives. They have many of the same issues and share many of the same problems as the other sexual first subtype with regards to relationship addiction and have even more dependency issues then the sexual/self-pres. They can lose focus and drift similar to the social/sexual subtype and their high energy can likewise be draining for others.
With this subtype, you have drama mixed with mental energy. What separates them from Fours who they might resemble superficially is their planning and future orientation. Their drama and intensity is focused on what they are going to do, not on what has happened. They are usually blind to their past, moving forward and not looking back."
Does that make sense for Garfield? No.
Now if you back up and take a look at my type call above, you can see why the e-type and Instinctual I chose fits Garfield like a glove.