In all the years i've been spending time in the bush, the scope i've depended on "by far" the most is Leupold. I can honestly say, i've never had one fail in the field, and after a few years of living with them in the bush on extended hunts, i even quit carrying a spare into camp.
Of course, i admit to being rather handy with a 44 mag revolver, and i ALWAYS carried that everyplace i went! Even when flying, i always had it in a shoulder holster and knew i coud use that if my rifle/scope failed....
I've seen quite a few scopes fail over the years, and there are brands i wouldn't even trust to use... But i still have the origional Leupolds on my "main" hunting rifles. Some of them i put on my guns around 1970 and have seen some unbelievable hunting conditions and still work today like they are new...
There may be some scopes today that are just as good as a Leupold, but what brand that's in Leupolds price range has a track record like Leupold does? Leupold has earned my respect for building a tough scope that i know will work every time i take it out into the bush, and that's were i'd put my money for any gun that i had to depend on.
After having said all of that, i'll add that don't mind having a cheaper scope on a 22 or some other plinker, and i'm thinking of buying a Mueller to try out...
DM