BROAD perspectives on "best"! :mrgreen:
In all seriousness, it probably matters more how much you're aware of any combination's pattern and poi at different ranges, maybe even the gun sight being more important than the load.
Winchester branded turkey loads were my favorites for many years, although I also like Federals.
Usually can't go wrong with these, with the best single shot size for many being #5's.
Winchester "Longbeards" have become the latest rage among reasonably priced "turkey" shells. However, imo, they are likely patterning too tight for many users who are not using an optical sight on their shotguns.
But you will get greater penetration with shells loaded with pellets "heaver than lead", HTL. ("Hevi" brand's "Mag Blends" are typically a great choice.)
Since these pellets penetrate so much greater, you can usually go to smaller shot sizes (such as #7), ending up with a pattern density more similar to #6's, but with the penetration more comparable to #5's. The big disadvantage is they cost more, sometimes a lot more, and it can be financially unpractical to do adequate "patterning" and testing like you might be more able to do with lower cost ammo.
Many are now hand-loading their turkey shells with "TSS" shot, which is much heavier than even HTL. This is generally not commercially available, although the closest thing to it (if not "it") is the Federal Heavyweight turkey shells. This has become my main "go to" turkey load in #7 shot size (as am always going for a head/neck shot).
IMO, if you have any factory "full" choke, you're fine for turkey hunting, and many might even kill more birds with a "modified" choke, as it's easy to miss a turkey at 20 yards when you're shooting a shotgun throwing a rifle-like pattern ---- that's where good sights can help.
All this in the context of most turkeys being killed under 35 yards, so if you set things up best for extreme ranges, you can be handicapping yourself for the more common distances you might be taking shots. And under 40 yards, it may matter little whatever shells you are shooting.
