My first knife: Buck 110.
I don't really have a nice fixed blade, only a surplus M9 bayonet, a cheap Imperial, and a $10 Mora. Otherwise, I would choose a fixed blade. Since my Buck 110 is sentimental to me, has the most history with me, and has NEVER heard me say, "Gee, I wish I'd brought *insert another knife here* with me instead of this big ol' chunk uh brass," then the Buck 110 it is! It has cleaned all sorts of game, filleted fish, been my main campin/cookin knife, and just an awesome companion...