What companies offer the best group health insurance plans?

Some of the most popular and highly rated companies across the US in general for group health insurance coverage include Blue Cross Blue Shield, Cigna, and Aetna. However, in some areas particularly outside urban centers each of these companies will have limited coverage or a very small number of participating providers, so one always needs to check whether a highly rated plan is good for their area before enrolling. On a local or regional level, there are several health co-ops and provider-specific plans that are very highly rated such as Emblem Health in New York State, the Geisinger Health Plan in northeast Pennsylvania and the Group Health Cooperative of South Central Wisconsin.