For my EDC "utility knife" (SS PE Spyderco Delica), I like a plain-edge, as it's less hassle to re-sharpen than a serrated-edge is, and a plain-edge seems to be more versatile for "everyday" cutting chores.
For my EDC "defensive/offensive knife" (SS SE Spyderco Police), I like a fully-serrated blade, as it should be better at ripping through clothing, flesh, and muscle.