Limiting yourself to only one of the two, like most here, I'd go with the 45-70.

That being said, my
first of the two was the 444, which I acquired in the late 60's. With handloads using the Hornady 265gr, it has performed well

for me on a number of game animals. It's been a loaner to a friend on a couple of successful Moose trips and on the last few trips north for Moose, it has filled the role of a spare rifle. It came in handy once in that role as well. A keeper

.
The 45-70, in the likes of Marlin rifles with their ability to handle todays powerful loads is, the next category up on the power scale. The first 45-70 in the Marlin for me, was the Marlin 1895GS. The straight stock design, especially when using heavier bullets in hotter loads the rifle can handle, can be a little hard on the fingers

. My Son now has that rifle and I've replaced it with a Marlin 1895GBL. Much more to my 'liking'. In it for a jacketed bullet, I'm leaning toward the 400gr and/or the 405gr. I've done some paper punching with it but haven't yet used it in the field, yet

. But,

to 'keep it company' I also have a Magnum Research BFR

.