My own preference is to keep kits small and lightweight so that I'm most likely to carry with me when needed. My objective is to survive until rescued (abt 72 hrs) - not to homestead in the wilderness.

As far as bang for the buck, over the years I've come to prefer these items:

-Doug's PSP - as a great starter kit
-Storm Whistle - big, but really really loud; maybe the Windstorm whistle
-Small Signal Mirror from countycomm.com
-Miox water treatment w/ 4-liter Water Tank (Platypus I think)
-Nalgene 32 oz wide-mouth water bottles
-Any knife with "Ritter" on it
-Vaseline-coated cotton ball firestarters
-Long K&M Matchcase w/ REI waterproof matches
-Brunton 8099 Eclipse mirror compass or Suunto M2 Leader baseplate compass
-Garmin GPSMAP 60CSx mapping GPSj or Brunton Geko 201 or 301
-UTM grids from maptools.com
-Eureka Tents - not best nec., but best bang for the buck