A very useful article appeared on Dec 21st, 2013 in the NY Times and many may have missed it (as I did)! It described in detail the choices of plans offered by the ACA. A good read before you get started!
Weighing Health Plans: The Devilish Details, by Tara Siegel Bernard.
A very useful article indeed. My take: focus on the maximum out-of-pocket expense for a given plan and try to keep that sum available. Coming from the Swiss health care private insurance system, co-insurance appears unnecessarily complicated. Therefore, I would suggest to stick to the above when choosing a plan.