The best and most efficient health insurance plan is one where everyone has, and is paying for, coverage. I am assuming this is what is meant by everyone in the pool. This is because when everyone has coverage, and paying for that coverage, the cost of health care drops quite a bit. Or at least it should!
When you compare the overhead of Medicare and VA to that of the private sector, or when you look at the failure of Medicare Advantage private insurers to add efficiency to that system, and when you compare our costs and outcomes to those of other nations who have universal health care, it seems clear the best system would be a public plan for everyone.