When I was on the marketplace, I couldn't tell much difference between the metals. I'd pick a network, all the tiers covered only the mandatory stuff as best as I could see; really same deal with all the networks, but different providers. Higher tiers had higher premiums and lower deductables... for me, I just went with bronze because premiums + out of pocket max was lowest; I'm sure there's portions of the curve where care would cost less with a higher tier, but I figured lower cost with minimal use and lower cost with maximal use is pretty good.
IMHO, health insurance makes it hard to do cost control of healthcare. Patients can't do it, because they won't know how much stuff costs until 6 months after service, so they can't really make decisions on cost. Providers can't do it either, they have even less idea of what things cost for patients, and they have an interest in providing more billable care. Insurance companies could do it, but denying care for economic reasons is hard, so they just go with denying care for beuracratic reasons; also, ACA insurers have revenue limits based on ratios to covered care, so covering more things allows them to get more revenue. Even government paid healthcare has trouble because everyone gets grumpy when they can't get all the care available.
IMHO, health insurance makes it hard to do cost control of healthcare. Patients can't do it, because they won't know how much stuff costs until 6 months after service, so they can't really make decisions on cost. Providers can't do it either, they have even less idea of what things cost for patients, and they have an interest in providing more billable care. Insurance companies could do it, but denying care for economic reasons is hard, so they just go with denying care for beuracratic reasons; also, ACA insurers have revenue limits based on ratios to covered care, so covering more things allows them to get more revenue. Even government paid healthcare has trouble because everyone gets grumpy when they can't get all the care available.