Most modern high-quality folders have a strong enough lock that I wouldn't rule them out as my only survival knife if compactness were very critical. Personally, I like to have a good quality folder along as well as a strong fixed-blade, like the old Ka-Bar. I also usually carry a Swiss Army Knife in the pack, even though I don't consider their blade as strong, by any means -- however, the can opener, saw & the other things can be very handy in camp.
A lot depends on where you're going to be, the type of undergrowth, how long and how far away from civilization (and help), etc. In thick brush I'd have machete along anyhow, and it's a lot more practical for cutting branches and building shelters than most "knives."
20+yrs in the Army, many years camping & hiking