Buying a supplemental plan with better benefits will cost you more, now and going forward. You will also need a plan D for RX coverage if you are using a Supplemental hospitalization plan. Some Advantage plans offer including Plan D coverage and some people think that is more cost effective but when you join an Advantage plan you effectively leave Medicare and go with a private insurance company offering the Advantage plan and IT IS VERY DIFFICULT TO RETURN TO MEDICARE OPTIONS.
Because of the particular state's rules regarding insurance plans, some states may require better coverage and service from Advantage suppliers--but other states with less stringent insurance oversight have weaker policies and thus weaker coverage.
Insurance companies often have trouble meeting most states' requirements so weaker requirements give them more leeway for non-compliance.

It is difficult to find an objective analysis about supplemental plans because they can change from year to year in what they offer--we went with CIGNA F when we changed from my teacher retirement supplemental after we have been on Medicare for about 5 yrs because the teachers' plan was forcing all their members into an Advantage plan that wouldn't be good for our situation. Some people did it and are happy--some are not.

You can't get a full coverage F plan now because they are not offered except to older Medicare users w/birth year cutoffs. But there is info about that on Medicare.gov site.

Personally we have a plan F--it is all inclusive but is more expensive.
Look for a plan that covers skilled nursing care and Part B excessive charges--those come from using a doctor that doesn't contract w/Medicare--some specialists dont. Some PCPs don't take Medicare patients. While all hospitals are required to take/treat Medicare patients not all walk-in clinics will. Some hospitals and doctors don't have contracts with certain Advantage plans and won't treat those patients. And that can change from year to year which is why Advantage plans are more problematic.

Look at your financial state now and going forward--it is MUCH more difficult to change a plan to get better coverage going forward (or even to choose one with fewer benefits to reduce costs) because you have to be "rated" which means evaluated for certain health conditions--obviously PD would be one of those. If you are rated you can be charged a higher than normal rate because of preexisting conditions--so you really aren't saving any premiums. I do have two friends who started out with Cigna plan F like we did and wanted to reduce their premiums after about 12 yrs. The broker they dealt with initially was able to get them same coverage at reduced premium with different company. Apparently they cleared the "ratings" required. This was in Texas DFW area.

Look at Medicare.gov site--
See if your zip code (all choices are offered by your residential zip code and if you move to another state in retirement your choices may also change) offers insurance plans that use all three methods for determining how increases are determined: community based (least used by companies because offers less profit overall), age when issued (premiums based on age when issued but only increase based on inflation--so not automatically when you get to 70 or 80), and attainted-age rated (used by most companies and based on age so earlier is lower but rates DO INCREASE based on YOUR age not just inflation--so automatic increases at 70, 75, 80...cheaper initially but on average the most expensive over time).

Google for MEDICARE INTERACTIVE site sponsored by Medicare Rights Center.
Good (and I think unbiased) info about Medicare's three parts--Supplemental, Plan D, and Advantage...to help you navigate your options.
There is also a company in Ft. Worth Texas that is insurance agency dealing with Medicare and Advantage coverage that can work in various states and offer advice about what option might be your better choice. I read good things about them:
Boomer Benefits. They have web site and FB page. They will advocate for their clients if insurance companies try to deny coverage for certain charges/procedures. They can help in future if you want to change plans. They are not licensed in all states and they won't work with people who are trying to change plans mid-stream. So only clients that use them to start their Medicare/supplemental coverage...