which is worse

All 3 of your reasons seem the same to me.
They don't like sex - that's easy, it's incompatibility.

How about - I like sex just not with you. I prefer a computer screen and my computer. Again its incompatibility.

To me the toughest reason would be a medical condition.

What about option 4: disgust - you simply aren't good enough for me to have sex with ...

I think there are a couple of flaws in this.
1- There is also "Health" issues - and if the partner is willing to do anything about them.

As well as "I don't like you and don't want to be married to you but I have a good life and don't want to give that up but I WILL Taze you if you come near me"
Which plays into all of those.

I agree with bballgirl that "Medical" should also be included in the list. The reason I put it in quotes is that sometimes the medical condition is truly a physical malady diagnosed by a doctor. Other times, it is more "subjective" and has not been diagnosed and treated by a doctor. On that, I call bullshit, and it is reclassified as "indifference"

I would order it as follows from "most acceptable" to "least acceptable":

- DIAGNOSED Medical Condition: This is not their fault. If there is a physical limitation that prevents them from intercourse, however, there are other ways to be intimate. For example, let's say the gent has ED or the lady experiences extreme pain. Totally understandable if they are averse to PIV sex. Their condition is probably also extremely embarrassing for them. But they have hands, a mouth, and plenty of other ways to satisfy their partner. If they use their condition as a crutch and just don't care enough to do these things? Then I bump them down to the Emotional Indifference category.

- Aversion: I think some of this depends on the reason and whether it was disclosed before the marriage. If it was advertised that sex was something that was a no-go and you married them anyway? Much of that is on you. If it came up later? That falls into bait/switch and drops to the indifference bucket.

- Distaste: Again, it depends on what bill of goods you were sold in advance. If you knew they thought sex was filthy and proceeded to marry them anyway? Much of that is on you. But if it turned gross the moment rings were exchanged? Again, bait and switch and it drops to the indifference bucket.

- UNDIAGNOSED / UNTREATED Medical Condition: If they think they have a medical condition and don't get it diagnosed or treated? Straight down to Emotional Indifference.

- Emotional Indifference: To me, this is the worst one. I am assuming that your needs have been expressed to your spouse and they are indifferent to them. There is no medical reason why they cannot have sex. There is not an aversion or distaste. They simply don't care. That isn't to say they even have to be mean about it. But they made a promise to have and to hold and (usually unilaterally) have refused to uphold that promise (while usually expecting all the rest of the promises to be held up on the other side). As wewbwb correctly says, if they are there because of a comfortable life and are just indifferent to your needs? That is emotional indifference.

Emotional Indifference, in my opinion is the worst of these, and where most of our situations eventually land (yes, I know not all...I can already think of exceptions). This is a CHOICE on their part. Because of that, it is probably the toughest to deal with. Why would they change if they are happy the way things are and indifferent to your needs? It is really hard to cure "don't give a shit" on a sustainable basis. You might get some reset sex, but nothing sustainable. Even when divorce is thrown on the table, it often introduces a flurry of interest and promises, but no lasting change.

This doesn't necessarily make our spouses evil or bad people (although some can be pretty nasty), but just recognizes the ultimate answer to the "why" question. They are indifferent to their spouse's needs, and given human nature, it is almost impossible to make sustained change on something you're indifferent towards (change requires internal motivation). In my opinion, that is why indifference is the HARDEST and WORST one to deal with. It is also why so few of us are able to choose the "stay" option and most of us eventually move to outsource and finally to leave.

I agree with all of this, but maybe because i am too close to the situation to really get it, i don't see an option to which i can ascribe my partner's narcissism. It is on me that every excuse ever given to me was reducible to emotional indifference, yet i elected to stay anyway. However, recently she has shifted her excuses to more of "i never thought you were good enough to share physical intimacy with you." This to me seems beyond emotional indifference and more contempt and disgust. I know the net result is the same, and i am working on it. But i think that this contempt hurts worse than the emotional indifference.

Likely the most common.
Like, suppose Zeus descends waves his hand and everyone gets divorced here, tomorrow.

Does everybody seriously expect their partner is never going to seek sex again with someone else? Maybe go to some trouble to have it? Get fit? Get dressed up? Risk, emotionally?
That's it for the rest of their lives? Celibacy?