I'd strongly recommend the Express Sights Scout scope mount for a lever-action rifle. I've got a Marlin 336 with one of these, topped with the Leupold 2.5x Scout scope with coarse reticle. For "dark" hunting in thick brush, it's outstanding! Both eyes are used to find the target, and then as the rifle comes to the shoulder, the shooting eye looks through the scope to pick up the target in the reticle. It's the fastest sight system I've ever used for a snap shot, and I find it wholly superior to iron sights for even close-range (25-30 yards) work. Of course, at 10 yards, the scope is a bit superfluous, but then I have never had such an opportunity!
If a scope is not desired, then I strongly recommend either the Express Sights Ghost-ring setup, or the similar sights produced by Jim Brockman or Wild West Guns in Alaska. All work pretty well. I don't know which is the toughest, in terms of ability to stand up to knocking about in a hunting camp, but I think that WWG's sights seem to be the best suited to take this kind of abuse. However, those who swear by Jim Brockman's sights would doubtless champion their choice vociferously... I would agree that the Express Sights system is the most "fragile" of the three, but that's relative - all three are pretty tough as far as everyday use is concerned.