I'd also vote for an AR-type rifle. As several people have noted, the ergonomics and accuracy of the AR15-pattern rifles are much better than the Mini-14 or the M1 Carbine. Ambidextrous safties are easily available for the AR. I'd eliminate the .30 Carbine anyway, since the .223 is less expensive to shoot and probably more effective. Good 20- and 30-round magazines for the AR are generally less expensive and easier to find than those for the Mini.
I doubt, for the uses you mention, there would be a significant difference in reliability between any of the three weapons you mention.
For your purposes, I'd also choose the shorty configuration, with the 16" barrel. It's much handier as a defensive weapon. The group purchase of the carbines at AR15.com has been the topic of a few posts here on TFL, and while this gun does have some good features (lightweight M4 barrel profile, flattop receiver), other parts are pure Walter Mitty (the faux flash suppressor and the pinned "telescoping" stock). I'd just get a carbine with a bare muzzle or real muzzle brake and a solid stock(preferably A1 length), assuming a pre-ban rifle is out of the question.
Olympic Arms recently brought out a little carbine they call the ".223 Plinker." This is a politically sanitized AR-type with an unlined, bare-muzzled 16" heavy barrel and a solid stock. It has old-style A1 sights, which are harder to adjust, but simpler and more rugged. Once dialed in, the A1 sights should be fine for plinking and defense. Putting A2 sights on a shorty seems overly optimistic to me, anyway. The receivers are cast rather than forged, but I doubt that will matter for your purposes. Besides, the Ruger is made of castings, too. Suggested retail for the Plinker is $599, though I've seen them for $525 (you can get them with a factory muzzle brake for $35 extra). This isn't much more than a Mini-14. You can check it out at
http://www.olyarms.com.
If you really wanted to go all-out, of course, you could get an AR carbine with forged receivers, chrome-lined 14.5" M4 barrel, competition muzzle brake, flattop upper with Trijicon ACOG and backup iron sights, handguard-mounted SureFire light, and a trigger job. It'd be nice, but for plinking and defense, the Olympic Plinker would probably serve just as well, and save you $800 that you could use to buy about 6,000 rounds of ammo. Or you could spend the savings on a good training course, and learn how to really use the rifle.
You can go nuts with add-ons with the AR, but most of these are just for appearance and pretty useless on a plinking/defense rifle. A sling and some good spare mags are about all most civilians really need.
Mike