My favorite(s) have changed over time too. I say favorites because I don't have just one either. It's currently my Spyderco G10 Caly3, G10 Dragonfly, and my mainstay mini EDC for years, the Vic Midnite MiniChamp. My Ritter Mini Grip, regular Mini Grip, custom Vic Farmer with HA III scales, scissors and pocket clip, Wenger Safari (discontinued several years ago). I've always really liked the Ladybugs too and am currently EDCing the H1 model.
For fixed blades (which I don't have too many of) it's my RAT RC-4, RAT Pack RC-3 and Fallkniven F1.
EDIT - I forgot to mention another fave and mainstay EDC for years - the Vic Huntsman.