From the experiences of friends and family, I recommend the AARP/United Plan F or G Supplement.
One warning. At initial sign up time do not just compare prices among carriers and choose the cheapest because the plan is the same regardless. The cheapest may be a plan or carrier with very little business or a unique pricing strategy. That carrier can increase disproportionately. AARP's Supplement will increase annually but the volume of participants is so high that the increases are reasonable.
You may hear that you can change plans during the annual enrollment. On supplements, that is a limited right. The insurer you want to switch to has the right of declining you. So, you may well find yourself locked into a plan that has out of control increases.
I knew someone on disability and they picked the only carrier offering Plan F in their state to those under 65 and on disability. It was something like $150. Before they turned 65, it had risen to well over $650 because the plan had such adverse selection by insured persons, only those with high costs. They tried to switch but were turned down. Fortunately at 65, they became newly eligible and AARP then took them. This is a seldom discussed topic but think of your selection of supplement plans as a lifetime selection when deciding. Choose a carrier with a lot of Medigap customers in your state.
I strongly discourage Medicare Advantage. Even with the best, you may face a limitation on doctors and hospitals available to you. The worst situation I knew was a patient who needed a lung transplant. Lung transplants require you to live close to the hospital so you can get there immediately if a lung becomes available. Also it requires you to live near for six months or so after the transplant and to have a caregiver with your there. Their plan only had three hospitals in the country for lung transplants. One in FL, one in MN, one in AZ. They lived in NC near one of the best transplant centers in the country. Fortunately, they survived until enrollment time and moved to traditional medicare and a supplement. They received their transplant 10 miles from home. It's not enough to check your existing doctors to see if they are on a plan. You have no idea what the future holds.