Survival Knife #1 = DFCG
Like = Bombproof shelter builder, firewood baton, etc.
Survival Knife #2 = Swamp Rat RMD
Like = Does everything the DF doesn't.
If I were going to have one survival knife it would be a Swamp Rat Chopweiler.
I believe in a "trifecta" though....
Small Fixed Blade = Scrapivore or Rodent Solution (preferred)
Medium Fixed Blade = RMD (preferred)or S5CG
Large Fixed Blade = DF (preferred in trifecta) or SOD or Chopweiler