I guess it would depend on what you want to use the rifle for. The .30-06 is a more powerful caliber, with a wider choice of bullet designs for hunting major game animals.
The .30-30, it is said, has taken more deer than any other type of rifle, at least in North America. Traditionally considered a "brush gun," which means the ability to shoot through small brush without much bullet deflection, .30-30 ammo options are somewhat limited, but time proven. A few years ago Hornady developed their LeveRevolution ammo, which can turn a .30-30 lever gun into an honest 200+ yard rifle.
In those endless gun forum "what if" discussions, if I could only take one rifle in any given situation, I would take my Marlin .30-30 with LeveRevolution ammo. Also, Marlin is now making a tactical lever gun that you might want to look into as well.
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