“It’s not an ancestrally appropriate food.”

Unfortunately, that makes perfect sense to me. But for now, I’m going to gloss over that part and tell you what’s better and worse anyway.

Organic is always a good sign. Just as important and maybe more is: grass-fed, and preferably “100%” grass-fed.

Stay away from anything “skim”. You want the fat for fuel, especially in keto terms.

Aged is good too. More time for the lactose to get eaten up and processed before it goes into you. Pasteurization, not so much.

The source animal matters a lot. Generally, goat and sheep (feta, manchego) are just better. Also, one theory says “buffalo mozzarella” is from buffalo milk, and that’s a good thing in America because all buffalo are mandated to be 100% percent grass fed. (I’m not totally sure on this–study your labels.)

If you have to go cow, try to make it from A2 cows rather than the far more common A1 (it’s a gene thing).

Beyond this, the most convincing guy I heard said blue, gouda and Swiss in that order. Also there are some specialty Euro-varieties I haven’t had any luck finding anywhere, called parmesan-reggiano and romano pecorino.