the "best"? if there was such a thing, everyone would already own it.

there are some really excellent ones, lots of good ones, but far too many poor ones.

in the end it comes down to what fits your needs, your price-range, feels good in your hand, and what knife you enjoy using.

rule #1: buy the best quality you can afford. cry once.

there is no one answer. hell, after buying edged tools for over 50 years, there doesn't appear to be even a couple of handfuls of knives that all-together meet my every need.

for survival alone i usually carry more than one, which might include a tiny SAK classic in my watch-pocket, a SAK Champ & a leatherman in my pack, a locking single-blade folder clipped to my front pocket, maybe even a 5" fixed blade on my belt and a large fixed blade camp knife tied to my pack. seems like overkill even to me, until i leave one behind and regret it.