For the love of all that is holy don’t just assume that because the runway is long enough, that the town has the appropriate medical facilities capabilities to deal with your passenger once they become a patient.
O.k...wasn't going off runway length, but I think we're on the same page?
The issue is an airplane isn't an ambulance and if you only have the flight attendants that aren't trained EMTs and don't have that tool kit, that person might be losing a chance at recovery since every minute can count.
I think having medically trained able bodied pax would make me go for the larger metro adjacent airport, especially if they thought it was worth the time.
Right now I am leaning toward nearest suitable to accommdate a patient, since at least they will have the EMTs ready and a hospital somewhere, possibly an air ambulance. Going for larger metro area if we have medically trained pax that think the patient could make it the 20min or so it may take. This a bigger issue flying further west passing Colorado, Utah, Idaho, etc.
If you're at a commuter the resources are lacking at least in my expeirence.
Any larger airport will have a hospital. Don't overthink it.
At larger carriers like mine we have diversion airports that include that sort of info. We actually use a phone on board to talk to a medical team on the ground, who knows our position and will recommend diversion airports based on facilities and time. They will also call ahead to those facilities to ensure transport is set up and ready to go.
Having a phone to just pick up and get all that information would be awesome but it isn't an option sadly. Communication is a big unknown since I've never used dispatch like that and exactly what they are likely to know and what ATC might know is not certain. Add to that getting information to land normally and that is a lot to juggle. Half the battle is just knowing options in terms of airports.