357 Magnum, because everyone should have a revolver in 357 magnum, and you need a rifle to match.
357mag.
Handload it down to mouse fart loads for kids or small game or load it up with Buffalo Bore Heavy 357mag loads and shoot 158grn, .36caliber bullets going over 2,100fps; close to 30-30 performance and good enough for under 100yd deer shooting.
I also like the .357 for the reasons stated by others and because it's easy and cheap to handload. With prices I've had to pay for .22lr, and can shoot
almost as cheap with my .357 handloads.
As a bit of a novelty, I have wax bullets and special cases with oversized shotgun primer pockets (no powder used). I can shoot those dirt cheap. Fun at short distance. Sounds like a cap gun. Could probably shoot them indoors like some people do with air rifles.
And if I were to rely on a lever gun for home defense (I don't), the .357 would probably be my first choice, due to its greater capacity and quicker follow-up shots (compared to the .30-30 or most other lever gun cartridges).