Bronze. With the lower premiums it is clearly cheaper if you are a low user, and at least for me, it is cheaper is I am a high user. That surprised me a bit, but all plans have max out of pocket caps, and for me the bronze I considered had a lower OOP max than the gold. So between that difference and the cheaper premium, bronze is cheaper for high usage.
On the plans available to me, there was a range between $4500-$16,000 where gold was cheaper, but only $1200 max at $10,000 expenses. Bronze was cheaper for me outside of that range. It's over $2800 cheaper if I have no usage and $3200 if I have $32,000 or more in expenses.
I don't recall if this included the HSA benefit of the bronze plan, which for me gives me the ability to convert a little more of my tIRA to a Roth. That's a little hard to evaluate because I don't know for sure how much less I pay in taxes on the conversion vs. distributions later. Or I could consider the fed and state tax savings in my bracket, plus the additional ACA subsidy, if I didn't convert any more due to the HSA. If you're up against the cliff, the HSA reduction to income might be a much larger benefit if it keeps you from going over.
The other factor is which doctors are in each plan. Both my gold and bronze choices had the same doctors so it made no difference, but if they are plans from different companies that may sway you a lot. The previous year I would've had to pay $8000 more to go with a plan with my doctors, so I got the cheaper plan and just went out of network as necessary.
If you qualify for cost-sharing, that would almost certainly swing you to a silver plan.
I think gold, silver, and bronze are misleading in that they imply levels of quality of service, but I don't know of any way that's true. I recall someone here wanting to go bronze but their ex- wouldn't let them because the kids were on that plan and she wanted "better" insurance. I suppose there's something to that if you refuse to see a doctor because you haven't met your deductible yet (more likely on a bronze).
Plans are very different in different areas, and people have different needs, so I suggest you plan to run a spreadsheet and see how you'd come out for various medical expense amounts plus the HSA factor, after looking at the service providers available for each plan.