Saphroneth
Banned
Like so many of the "Best" discussions we have, the answers go back to the purpose the particular item was used for.
For the 1870's, in addition to the big inter-country fights, there were a continuous stream of local wars, rebellions, raids, mutiny's, insurrections, what-not that in total may have burned through as much rifle ammunition as the big wars did
If you are only considering two professional armies standing across a field from each other, that's one discussion. If you are considering the many fights of that era involving a few hundred combatants, who may have arrived on-scene on horseback, canoe, via jungle trail, et al; the weapon of preference is probably different.
Which is one reason I think the M-H is only in the running if we allow the later cartridges. Locked to the wrapped-brass cartridges, it's a little too unreliable - and a jamming rifle isn't important in a skirmish line of thousands, but it can be quite important and perceptible in a company firing line fending off thousands of angry men with mangoes - er, I mean, spears.