For just a flavor of the principal dissenting opinion, try this:
I respectfully dissent. The Equal Protection Clause does not license judges to strike down any policy we disagree with. It instead grants the states leeway to tailor policies to local circumstances, while providing a carefully calibrated remedy for truly illicit discrimination. No such discrimination appears in these cases. North Carolina and West Virginia do not target members of either sex or transgender individuals by excluding coverage for certain services from their policies. They instead condition coverage on whether a patient has a qualifying diagnosis. Anyone—regardless of their sex, gender identity, or combination thereof—can obtain coverage for these services if they have a qualifying diagnosis. And no one—regardless of their sex, gender identity, or combination thereof—can obtain coverage if they lack one. There is therefore nothing about these policies that discriminates on the basis of sex or transgender status.
This is truly "Alice Through the Looking Glass" stuff.
The real question is what the Supreme Court will do when it gets its hands on this issue. That is a question, right? And not a foregone conclusion?