I always believed the big conical was the way to go. .44s are a known, they work, but the big conical of full .50 caliber out of my Hawkin Hunter Carbine is pretty impressive looking.
But, I've read a lot on this site about the killing power of the round ball. Not sure why a round ball should be that good at killing over a conical, but I've got an open mind. I've got no hunting experience with round ball, though, so I yield to those who do. I STILL think the big conical would be hard to beat, though.
Now, my Hawkin Hunter Carbine has a twist rate of 1:25 which is quite fast. It shoots Saboted 240 grain .44 pistol bullets and really heavy 385 grain hollow pointed Hornady conicals really well. I've tried lighter conicals and I suppose they over stabilize because I can't hit squat with 'em. Balls? Forget it.
I now want a 1:66 twist gun to shoot balls or perhaps a 1:48. Got a friend with a 1:48 gun and it's pretty accurate with light conicals and patched balls. I still like the hunter carbine, though, for hunting. Those heavy conicals are pretty awesome. I am quite confident they'd stop a good sized boar or whatever I wanted to whack with 'em.
That probably didn't directly answer your question, but it's some thoughts on the subject.