What tends to be cheaper in the long run, a Medicare Advantage plan or Medicare Part A+B+D?
The answer depends entirely on what your specific healthcare needs are and, if Medicare Advantage, which of the many plans you choose.
Most Medicare Advantage plans include prescription drug coverage. With Original Medicare, you have to purchase Part D for drug coverage. Deductibles, copays, and coinsurance amounts are all different between the two. Medicare Advantage has an annual out-of-pocket maximum to protect you against catastrophic costs, while Original Medicare does not. And the list goes on....
In addition to the costs, there are non-financial issues to consider, such as choice of healthcare provider and pre-authorization requirements for certain services under Medicare Advantage.
Here's a two-page summary from the Medicare Rights Center that will help you compare and contrast the two:
Differences Between Original Medicare and Medicare Advantage Plans
Beyond that, you may wish to get in touch with your State Health Insurance Assistance Program (SHIP). It's a confidential, free service and they can help you decide which direction is best for you.