I personally carry the Mora knife. Their cheap (12-15$) and they have a tough carbon steel blade. They are a good size and can be used for a wide variety of survival task. I wear mine on my neck and have a lighter taped to it...like in Cody Lundins book.
I have many knives, but only three-four I would trust my life with. Right now, my primary "survival knife" is a Diving Sparrow NBS Bravo (Northern Bushcraft Survival Tool) Site - http://www.dskw.ca/ and my other go-to knife is a custom Sugar Creek Campcrafter (Kephart design) Site - http://www.sugarcreekknifeworks.com/Pages/default.aspxI have done reviews on both blades. The Kephart is here - http://www.woodsmonkey.com/index.php?option=com_content&view=article&id=681:sugar-creek-knifeworks-campcrafter&catid=34:knives&Itemid=55The DS NBS is here - http://www.woodsmonkey.com/index.php?option=com_content&view=article&id=779:diving-sparrow-knife-works-northern-bushcraft-survival-knife&catid=34:knives&Itemid=55
I recently purchased a Schrade SCHF9 Extreme after a buddy got one at Bass Pro, and have been toting that around for my "daily living". 6.4" blade, 5.6" handle, 1095 High Carbon Steel, Kraton handle, 15.9 ounces, and it included a nylon sheath which I went ahead and made a Boltaron sheath for. I'm very impressed with it overall, as I normally have my Busse Team Gemini M Combat Grade for my daily driver. I like the slight belly and thickness of the blade, but the handles are fat and slightly harsh on the edges. Not my choice of a grip but it doesn't impede anything I try with it. I think it does a good job and is a great knife for those out there who may not have the income to support buying a really expensive knife, and yet want to have something reliable at the same time that they can trust. I got my Busse off of another guy who wanted to trade for some firearm maintenance. So I got lucky. But I'm going back to my Busse this week. BLADE LENGTH: 6.250"OVERALL LENGTH: 11.750"BLADE WIDTH: 1.5"BLADE THICKNESS: Approx .220"GRIND: Flat SaberSTEEL: INFIHARDNESS: 58-60 Rc