First up is the Gerber LMF II. Whether you are talking about the ASEK, the Survival, or the Infantry versions of this knife, they are all the same except for the accessories they come with and the colors. (There is one small exception which is the IR resistance built into the Foliage Green knife.)
The Gerber LMF II knife has holes in the handle to allow it to be lashed to a staff for making a spear. The butt cap is solid and can be used for hammering, breaking glass, or as a blunt bludgeoning weapon. It has a section of the blade that is serrated which makes for quick cutting of rope or small limbs for tinder.
One draw back to the serrated section is sharpening. In an extended survival situation without the proper sharpener this area of the blade could become dull.
Next up is the SOG Seal Pup Elite. I like this knife because of the size and weight. The overall length is 9.5 inches. It is a very light knife as it weighs in at 5.4 oz., compared to the Gerber LMF II that weighs over twice as much at 11.4 oz.
The SOG Seal Pup Elite doesn't feel heavy if strapped to your lower leg, something that would be difficult with the Gerber LMF II. However, the SOG Seal Pup Elite is not as versatile in the field as the Gerber LMF II. It is extremely good at being a light quick weapon, and it is definitely up to whatever cutting tasks can be thrown at it. This knife can be bought with or without the serrated section which is not an option with the Gerber LMF II.
Basically it comes down to what you are looking for in a survival knife. If I had to pick one knife to take with me into a survival situation it would be the Gerber LMF II. But if I could take two, I would take the SOG Seal Pup Elite along as a weapon.