Medicare Advantage is not the same as Medigap. I'll be 65 in October so will be messing with that problem by August. My husband has an Advantage plan and I'll probably go with that since it works for our doctor. I would find a doctor(s) in your area and see what they take and work backwards, based on what they take and what gives you the most bang for your few extra bucks.

I found this a tiny bit useful: Medigap vs. Medicare Advantage Plan - Which is Best Medicare Supplement - AARP