This has been a frequent topic on this and other boards since someone figured out that oil works better than bear grease in the winter. The frequently reached bottom line is that any gun oil or lubricant, or otherwise will just about do the job as long as the job is done. Leave any firearm dirty or neglected and it doesn't matter what you use. Corrosion X, Break Free, and even WD 40 are good long term rust protectants. There are other products out there that leave a wax film after use that I have grown to like, and I believe they are better for long term storage. Grease has its adherrents and I believe there are occasions for its use.
Bottom line for me is this: I want to know that what I currently use is the best for the least. It's shocking to me how gun oil and the like is sold at a premium by the ounce! After all, no one has up to this point explained what ingredients and percent compared to the the base oil their brand of super gunk has to justify that outrageous price! Corrosion X is good, and so are a bunch of other products out there.
I currently have on hand enough to clean and lube my firearms for the next several years and probably will be given or come by even more than I'll ever use. Still, I like the Corrosion X probably because their advertising makes me think I'm doing my firearms a favor.