You didn't post details about your income, but I'll assume that you make more than 4x the FPL for your family size. If you make less, depending on the state in which you live, you may be eligible for subsidies.
If you have not done so yet, I encourage you to go to healthcare dot gov and compare all the plans available. If you don't use your benefits much, you're best off with the lowest premiums. However, many of the cheaper bronze plans have identical benefits of the silver and gold plans, but have much higher deductibles and copays. Depending on how much insurance you use, a more expensive plan may actually be less out of pocket for you.
The other big cost differentiator is provider networks. Many insurance payors are reducing their costs by squeezing providers, resulting in much more narrow networks as doctors decide not to accept the squeeze. Be sure that the plan you choose has doctors you can actually see.
ethically I don't think it's right to plan on utilizing a social program like Medicaid for low-cost medical insurance in ER.
That's certainly your choice. You should be aware, though, that if you're eligible for Medicaid and you opt out of it, you are not eligible for insurance subsidies. It could be an extremely expensive decision on your part. Medicaid no longer has an assets test (for most programs - some carve-outs continue to have them). This change was made to simplify application process, and to accommodate folks who found themselves out of work but still had assets. With this change, people who lost their jobs could immediately qualify for Medicaid without having to sell their houses and cars, which is how the plan worked prior to the Affordable Care Act.