Whichever suits your needs/wants. What's it for? (plinking, hunting, etc) A question like this gets ppl saying to buy whatever their favorite is. You've already got a well rounded group so not really a niche to fill. I'm the same point (and then some) as any real use I'll need a firearm for is well covered. Getting into making various models more personalized and having work done on them to make them more unique. Maybe go that route. Change configurations, chamberings...make something different.
Blkhawk73 is correct. Trying to buy something that someone else likes isn't the way to go.
I suggest you go to a gun shop or 3 & look over their selections. Go to gun ranges & try different guns. I'm sure you'll find something you'll want sooner or later,,,!
I guess it depends on whether you want a handgun or a rifle. I'd say a Redhawk in .44 Mag or .45 Colt or a Hawkeye in .243/.25/06/.280/.30-06 would suffice for nice a middle ground between the .45-70 and the .223.
I see a 6" gp,, and a SBH (what barrel length is the SBH.........7.5"?) If it is a 7.5" then........
if you're looking for a handgun, maybe a 4" or 4 5/8" revolver in caliber of your choice. if you choose a 45 Colt, then go Ruger so that it can handle the heavier loads. 44 or 357, then your choices are wide open.
If you want a centerfire rifle, then 270 or 30/06 bolt action.
That's a good problem to have! I can definitely see the 4-5/8" .357 BH, as 1's on my 'to do' list.
If you want to expand your horizons a little with a Blackhawk, what about a .30 carbine, or a .41 mag? My 6-1/2" .41 mag is the sweetest shooting gun I own. It's fun to shoot, a good hunting round, and a blast to reload for - really opens up the possibilities!
And a .30 carbine BH with a 7-1/2" barrel would be a blast - literally! Ammo wouldn't be too bad, fairly easy to find, a good plinker, small to medium game gun as well!
Or a .44 Special...
Or a Single Six.....