We were on ACA for 4 years before qualifying for Medicare. We opted for an Advantage Plan through Kaiser instead of a Medigap plan. Our Kaiser Basic Advantage plan was +/- $40/month for 4 years until this year when the premium changed to $0. So, on the surface, it looks "cheaper" than Medigap G.
Beyond the Medicare B ($174.70/month)and Medigap G (or Advantage premium in our case), I have been surprised by the medical costs my DS and I have incurred (doctor co-pays, dentists, procedures, etc.). Seems like the check-engine light comes on every year. Our out-of-pocket costs (beyond the premiums) have been:
2019 - $7,200 (back surgery and costco hearing aids)
2020 - $4,500 (rotator cuff)
2021 - $5,100 (knee replacement, eye glasses)
2022 - $7,600 (crown replacement was $2,000 plus lumpectomy/radiation and eyeglasses)
2023 - $4,000 (other rotator cuff)
2024 - $4,700 YTD (including new costco hearing aids @ $1,600 and new eyeglasses @ $600)
Pretty consistent at $5,000/yr plus one off events. I consider us healthy, active seniors without obvious healthcare problems - yet aging continues to catch up to us. Knock on wood, 2024 looks like a low cost medical expense year.
Even though Medicare/Medigap do not cover dental, don't forget this piece as it gets very expensive very fast.
Hope this helps a bit.