HealthCare.gov is a decent large government big UX project. It turned out pretty good, all things considered.
IMO, I wish the government would have found and replicated (or contracted?) the service I had used before HealthCare.gov existed [0], and just bolted on the subsidies and other things they do. It is still functional today, and I've used it to get insurance since HealthCare.gov went live (specifically off-marketplace, but marketplace-compliant insurance), and it is my first stop anytime my HealthCare.gov insurance tells me the price is going up. I compare with eHealthInsurance, if eHealthInsurance is cheaper, I go with it instead.
IMO, I wish the government would have found and replicated (or contracted?) the service I had used before HealthCare.gov existed [0], and just bolted on the subsidies and other things they do. It is still functional today, and I've used it to get insurance since HealthCare.gov went live (specifically off-marketplace, but marketplace-compliant insurance), and it is my first stop anytime my HealthCare.gov insurance tells me the price is going up. I compare with eHealthInsurance, if eHealthInsurance is cheaper, I go with it instead.
0: https://www.ehealthinsurance.com/