Don't be selfish. Get something that you can share with others and introduce some of them to shooting and firearms. The AR is the best for sharing, especially with children and young people.
The single action revolvers are also good provided you can use light enough loads for everyone. 44 Special is not light enough for children with no prior handgun experience, but .32 S&W Long in a .327 could be hand-loaded suitably and you can get that in the SP101 or the Single Seven. Rimfire handguns have traditionally filled this roll. That's what I have also, but I'll trade it out for a centerfire .32 so I can shoot lead-free primers and at least plated bullets. I wish there were a better selection of lead-free bullets in .32 caliber, or in even smaller caliber centerfire handguns, but there just isn't.
In the lever-gun, .45-70 doesn't have as broad appeal as one of the handgun cartridges. The two problems I see is the ones chambered for magnums (.357, .44) typically don't cycle the best with their lighter counterparts (.38, .44 Special) and so maybe .45LC is better or just loading low-pressure rounds in the magnum caes. Second, and more importantly, the length of pull is too hard to change for different size shooters.
The AR-platform comes with easy-to-adjust length of pull, an action (charging handle) that is easy for kids to pull without a lot of finger strength, detachable magazines that allow them to load the firearm without handling toxic ammunition (compared to lead .22LR), but also an excellent selection of components (primers and bullets) that are free of heavy-metals. Importantly, the full-length rail or M-LOK fore-ends also allow sights and optics to be set where they're compatible with short lengths of pull. When you cut down the stock on a lever gun or a semi-auto or bolt-action .22, the kids' eyes will be too close to the receiver-mounted scope or other optic with long eye relief. With full-length rails, you can just slide it all forward.
.223 is better for kids than .22LR because lead-free primers are available that reduce kids exposure to lead styphnate salt. The performance of lead-free bullets in .223 is also a lot better than lead-free .22LR projectiles which are typically limited to very short ranges. .223 also has a suitably low recoil.
The AR-15 type firearm in .223/5.56 is an ideal first firearm for kids and first-time shooters of every size and age. Maybe you don't have kids in your life, you're not a dad or grandpa or uncle or neighbor to any, but there isn't really anybody you can't ask, "hey, want to go shooting with me?" and then take out an AR with them. With a Super Redhawk or a .45-70, you'd narrow your audience quite a bit.