If I had to pick one knife to survive with, it'd likely be my NMSFNO.
After that, I'd go: .22" or Skinny ASH, SAR-6, SFNO, TG LB, BJ.
I would never carry just one knife though, so I don't think about this all that often. I usually have a big/large piggyback setup, or if I'm not covering much ground, I'll carry my B11 in my pack, and carry a 6"-7.5" knife strong side and a 3"-4" knife on my shoulder strap or on the back or weakside for cross draw.
Get the TG LB. it is an incredible knife in my opinion, especially at the cost you can buy one at from the Busse right now.
Otherwise, get a SY or SR knife. If you don't like any of the designs available right now, you could pick up something like the chopweiler off the exchange if one comes up.
SY and SR knives are incredibly durable and I wouldn't hesitate to solely rely on one in a survival situation.