i've tried just about all of them (i welcome suggestions from others re: new ones to try) and have conducted my own (very unscientific) tests, mainly salt water corrosion.
break-free clp overall is the winner, easily available and is a very good rust preventative.
eezox is a superb rust preventative, but be sure to apply it very lightly.
corrosionX ranks very highly as well.
rem-oil (spray) i would rank somewhere in the middle, by no means the best but definitely better than nothing at all (as compared to the test sample).
militec-1 is the only one that i tested that did not do well at all re: salt water corrosion...for whatever reason. this conclusion is based upon the free sample they sent to me awhile back, maybe they have changed the formula now, i don't know.
one thing that does stand out is that w/ almost all a very light coating will do the job; i always tended to apply too much, and i believe that especially with firerarms this could cause problems.