If you are telling me I can only ever have one gun, and it has to be a long gun - none of these 3 make the top 10.
To reply to your post, the answer is 303. I am going to assume from your info that this will be some variant of Enfield, which means accurate, slick bolt action and 10 rd magazine fed by stripper clips. I can maintain a pretty good rate of fire with my Mk5.
The real qualifier here, is your indication of 'homestead' defense and not 'home' defense. Inside the house, 12ga is king of stopping power. But if you need to hold down a couple acres and engage coyotes, wolves, bandito's - etc, the longer range and stopping power of the rifle win the day.
To me, with a single gun qualifier as stated, I would be looking at a semi auto, detachable magazine carbine. Take your pick of AK/AR/ Mini 14. I would even take a lever action 30/30 over the 3 listed options.