Opinions are like buttholes, everybody has one. Here's mine...
The trend these days seems to be big charges/lighter bullets. I suppose this is for increased muzzle velocity and less downrange bullet drop. I PERSONALLY know of 6 muledeer bucks and 1 bull elk that were hit and unrecovered to lighter (240gr) bullets in the last year. Nikon is marketing a muzzleloader scope with range compensation built in specifically for a charge of 150gr and bullet of 240gr. IMHO 240's are too light. Even with 150gr of powder you're unlikely to get a pass through and unless you make an excellent shot, little to no blood, and recovery becomes iffy. I hit a smallish buck last year standing broadside at 50 yards. The shot may have been an inch or 2 higher than I would have liked it to be but was definately in the lungs. He shuddered, hunched up, staggered just a little and I expected him to go right down. He straightened himself up and walked out of sight into the brush. I never found him and I'm positive he died, just not where I could find him. I changed my bullet to 405gr this year (I have an elk hunt coming up and don't want to switch bullets again) and changed my tactics too. From now on I am going to shoot my muzzleloader to break shoulders. I may not get an instant kill but at least I'm not going to lose another animal. The buck I shot this year with the 405 took 1 step on his remaining 3 good legs and fell over dead.
I'm sure others will disagree with me but my advice is to go with a heavy bullet and put it in the shoulder. And do your best to keep your shots under 100yds. These rifles are high tech these days but they are still considered a primitive weapon for a reason. I killed a B&C pronghorn several years ago with and old style (not inline) rifle and a maxiball at 198 long paces. Pure luck and honestly a bad shot decision, just luck. I'm pretty sure I'd let that buck walk now even with the improvements in equipment.
BTW, the 405's I'm using are Powerbelts. HGit my deer from the front at about 60 yds. Destroyed his left shoulder, a few ribs and took the top third of his heart off. Pretty good for no power or expansion.