I'm one of those guys that drops by the local Ma & Pa and picks up a box or two of ammo every payday... So when the last panic hit I wasn't dead in the water, but I didn't exactly go to the range twice a month and blow through 100 rounds in an hour either.
That being said, at any given time I probably have around 300-400 rounds of plinking 223 on hand for my AR... but I also keep 3 30round mags loaded with 20rounds of green tip 5.56 each (why 20? Easier on the mag springs for long term storage IMHO).... and that's it. Those mags are the only thing I keep loaded and at the ready other than my CCW piece in my house... and they stay locked in a ammo can seperate from the cabinet. Safety first... especially with kids in the home.
...Now 22lr...?? IMPOSSIBLE to have too much of that... especially when you have kids in the home (that also shoot that is..)
In all honesty though... My 12 gauge pump would be my "go to" grab if I could only have one to take. Just my 2 cents... Your milage may vary.