Well... I obviously don't know anything about the insurance-related circumstances where you live. Personally, I'd have to say, although I've always had health insurance, that didn't result in me finding anything in the way of a competent therapist... (at least not from my perspective.)
To my mind, whether it's better to try to get health insurance, vs. trying to find a T with a sliding scale, is perhaps not so much the question. Of course, having health insurance is a good thing under any circumstances. But I personally don't know as it's necessarily going to lead to finding a better T. A T you feel comfortable with may be one who only accepts health insurance. But it could also be one who has a sliding scale fee structure. I doubt there's any direct relationship between the two, if that makes any sense.