This is almost an impossible question to answer, in part because there’s no definition of what you’re considering “best,” and partially because these things change over time.
Even if you define a list of what makes a residency best (eg: research, board pass rates, comfort on graduation, fellowship training, etc) it’s hard to say which is “best” because most of us don’t really know the data for programs from which we did not graduate. Also, it’s really apples and oranges comparing completely different specialties. Saying “compare the ortho program at MAMC vs SAMC” is hard enough, but comparing neurology to radiology? How does one even do that?
Finally, as you’ll see repeated multiple times within this forum, if you can get in to a top ranked civilian program it is probably better than any military program, but most military programs aren’t bottom-of-the-barrel.
What are you looking for, specifically?