Hmm, you gave a few different scenarios and really what I'd pick would be largely dependent on the scenario.
For general societal collapse where life goes on relatively normally but there is no real law to speak of my choice would be different from large scale riots, large scale organized anarchy, combat, or whatever else. Life goes on relatively normally and we can stay in our homes I'd basically be set up as I am now for HD but the AR and 6 mags would likely be added to the always loaded list.
For societal collapse where you are on the run I have a few thoughts. While a shotgun makes a lot of sense in many respects as it is so versatile with different loadings (slugs for distance, 00 buck for short range defense, and with different loadings it is good for pretty much any game in N. America) I think I'd stay away due to the ammo actually being pretty bulky and limiting the number of rounds. For my long gun it would depend upon whether it appeared more likely to need defense against individuals or very small groups or if it was larger groups (also, am I teamed up with others who are also armed). For simplicity and reliability I'd strongly consider my Winchester 94 in 30-30 or my .45LC Win 94 (though I'd prefer .44mag or .357mag for serious work over the .45LC since .45LC isn't quite as reliable out of a rifle). However, if serious combat was likely (against untrained roving bands) I'd probably either go with my SKS (reliable and durable) or my AR (more rounds). If I didn't need to go with what I currently own it would be between the lever rifle or an M1 Garand or M1A. The pistol would probably be my Taurus PT140 Millennium Pro (100% reliable to date) for when I want to be discrete backed with either S&W 65LS or 6" S&W 57 (hey, society has collapsed, I don't think I need to worry about MD's carry laws, or probably even keeping it concealed). If I didn't need to go with what I currently own the PT140 would probably be replaced with a Kimber Pro Carry or CDP Pro (1911 types have plenty of spare parts available so it would be possible to carry parts to fix nearly anything that might go wrong, and 1911s are easier for more people to work on).
For combat against the Chinese Army my choices would be much different. The semi-trained "insurgents" in Iraq do best when they stick to IEDs or potshots at our troops, when they stand and fight they get cut down like firewood. While the Chinese aren't up to US military standards, they are good and I haven't seen military training for over a decade and a half now. Standing and fighting would be suicide. I think it would be more effective for groups of Americans to act as snipers/sharpshooters. Especially in urban areas. For my handgun I'd probably go with the Taurus PT 140 M. Pro or Taurus 85 (highly concealable). For my long gun I'd prefer a very accurate bolt rifle or single shot if in the country (long-range accurate, possible to be passed off as a hunter). Since I don't have one now, if I had to go with what I owned and I would do rural sharpshooting I'd either go with my 30-30 lever rifle (give up a lot in long-range accuracy, but very easy to pass off as a hunter) or my AR (get back the accuracy, but better not get caught). For urban use I'd probably go with a .22lr rifle- it will kill and it is much more quiet than a centerfire thus making detection less likely. Well enough hidden I might go with the same as the rural rifles. In all cases, I'd limit myself to one shot so it would be harder to detect my location.
). Oh well, to each their own.
