One of the primary reasons Medicare Advantage has become popular is the sales commissions are MUCH HIGHER than for Medigap plans. Those commissions don't end after the first year either, they continue to be paid as long as the policy is held and that commission structure leads sales people to actively lie about Medicare Advantage vs. Medigap. Those increased commissions can easily add up to hundreds of thousands of dollars extra pay in just a few years for pushing MA.
People are told if they don't like their MA plan they can just switch to Medigap at a future date but that's a outright lie. The truth is that after the initial 6 month open enrollment period, the vast majority of people can never switch to a Medigap plan and are stuck with Medicare Advantage and its long list of disadvantages for the rest of their lives. Even the most minor of health conditions (such as medication controlled hypertension) can be used a pretext to deny coverage or substantially jack up Medigap rates.
Another common lie is that you can always go to any in-network MA doctor or medical center anywhere in the country. Again not true. In most places people are limited by specific geographic area except for occasional visits to medical providers other areas. If you have a world class medical center and doctors outside your coverage area you want to see too bad - computer says no. No one in customer service or sales will mention that. You have to read the 200+ page policy's fine print or you would never know.
If you or a loved one are approaching Medicare age be very, very careful before choosing Medicare Advantage over Medigap, despite how tempting it may look.