If I could have only one lube it would be BreakFree.

In high dust conditions Prolix is great stuff.

In highly wet conditions, Ballistol works great, it has been around since the early 1900's. The German Army used it in WWI, and WWII.

If you need a grease, then Prolix Xtra-T Lube, or Tetra Gun Grease is worth using.