There are alot of bests out there.
What is best is what works for your conditions, what your vehicles appear to like and what your willing to pay.
The best of the bests I would say are Amsoil and Redline.
Some other bests are Mobil 1, Pennzoil Platinum, Valvoline Synpower
Protection is a broad word. Protection from Cold?, Heat? Load?
Sludging? etc....