I've thought about picking up a Marlin .45-70 for years but just when I'm on the edge of jumping into the pool I wonder, "why?". One answer is "because I can and I want to" and if you just want to own a thumper you can't do better than .45-70. As a practical matter there are better rounds for almost every hunting/self-defense function.
If you want a lever then go with the .44Mag as suggested above to shoot lower cost than the .45-70. I've got 3 of them, all Marlins, and they digest Specials or Mag which is good enough for deer and black bear and hogs. Unless you are concerned about brown/grizzly bear the .44Mag has all the power you need. The .30-30 is a great deer round and the 336 has got to be one of America's most common rifles. And .308 is probably the most versatile round of all -- you can download for lower recoil or upload to take anything in the Lower 48, flat trajectory, longer effective distance for ethical hunting than the .45-70.