I love my Bushy Shorty, but I'd keep my DSA Carbine. Just about the cheapest military-style rifle mags at $5 each and a hard-hitting round with many applications.
For pistols...that's tough. If I had a Glock 19, it would be between that and my Kimber Custom, but I'd probably go with my Kimber. Cheap 7/8 round mags and 1911 parts will be available forever, and if we're ever restricted to FMJ in the future, I'd wanna stick to .45.
btip--you aren't a JBT looking to downsize us, are ya?[:P]