Most of them have their lenses made in the same labs as their competitors, so the $400 lens at LensCrafters (my former employer) often is no different from the $120 lens at America's Best (my fiance's current employer).
Go with the place that has the lenses and frames you like.
Does your insurance cover any optical cost? I'd start there if they did.
Seems like it would depend on the eye docs who work there, and without any other information you pay your money and take your chances. Anyone can probably do a refraction but you also want someone who can spot something going on in your eye that may be a problem. If they are optometrists who graduated from a decent school and have a few years of experience you should be OK. If you have a personal or family history of eye problems you might want to use an ophthalmologist.
Did you tell your current eye doc about your loss of insurance and ask if they could cut you a break on the fees? Better to stay with them if you are happy there.
I've had very attentive care at a Wal-mart and a half-assed appointment at a well-regarded private optometrist. I agree with ddowns that whom you see (rather than the name on the doc's door) makes more difference. Ask friends locally whom rthey have been pleased with.
An eye doctor at Wal-Mart goes through the same schooling and training as one in a private practice. I've used both in my life and haven't really found one to be better than the other except that Wal-Mart's glasses tend to be much cheaper. (I do currently see a private practice, but wouldn't hesitate to go elsewhere if necessary.)
And yeah, you can take a prescription anywhere. (I wear contacts, so I usually just order online since it's at least a little cheaper than from my eye doctor for the exact same thing.)