If you reload, or want a variety of factory ammo, get a 45-70.

If you don't reload, and want the load that seems to be the ultimate sweet spot in a 45-70, get a 450, the factory loads a 350 grain bullets running around 2,000 fps.

I have three 45-70s and two 450s - if I could only afford one, after all I've learned from Jackfish and others over the last eight (8) years, I'd get the 45-70.

Comparing or deciding between a 45-70 and a 44 magnum is moot.

Carrying a 44 magnum is fun, especially if your side arm is a 44 magnum revolver, and you shoot same loads.