Spyderco UKPK. I have EDC'd this thing every day for the last 8 months or so, which makes it my longest EDC. I just can't leave it behind. I have tried to force myself to EDC just my Squeak or Kiwi 3, or even my BobT Slipit, and the UKPK always tags along, even if it is just in my backpack. It even comes with me to the gym, staying safe in the locker while I carry the Squeak (doesn't bounce in the pocket of gym shorts).
It is just too good a combo of weight, blade size and shape, with speedy opening and closing, and no worries about legality issues here. That and I seem to be able to get it sharper easier than any of my other blades. The next challenger is an orange G-10 Wharncliffe Urban that my wife ordered me for Christmas. Hopefully that will be here next week. My prediction is that it just becomes a companion knife to the UKPK like all the others. Hah!