Retirement and Medicare with the right company is great. The government sucks the money out of your social security regardless of weather you opt for just the red white and blue card or go with a company (and there are many out there) that must give you more than the red white and blue card gives you. In my opinion you want to select a provider other than the red white and blue card. The government does not want to manage your health care they only want to pay other providers in the business to manage your health care. They require companies to give more than their "no frills" plan gives.
I did a few mystery shops to evaluate offerings by companies. It is great to be paid to explore your opportunities and options. I find the salespeople must be honest or they are sanctioned. They must sell you the plan you qualify for. The plan may be different in different states and in different counties. You are only able to buy the plans that are offered in your county. No matter what plan you settle on the government will take the same amount out of your social security check. There are different co-pays and formularies (prices for prescriptions between pharmacies that are "out of the pocket costs and they can vary greatly.)
I would not suggest which company is best but one must consider which doctors you go to, which accept medicare, can you go out of network to stay with your doctor, are you willing to switch if your doctor is not an affiliated doctor? What medicines are covered in your Forumulary? Which Pharmacies are available to you? Are those in your plan?
I get "silver sneakers" free membership in a health care facility. The perk the provider offers is free as they want you to exercise and be healthy rather than be sick and cost them money. They have in home wellness visits by a licensed nurse practitioner and they offer a wellness visit to your primary physician not to be confused with your annual check up. Is the AARP endorsed provider good for you or is another provider better?
Every year you must check and take the shops that allow you explore your options while you get paid to do it. Not all companies offer the plan that is good for me. Take those mystery shops and get paid to explore your options.