The whole Spyderco Slipit line. Legal almost anywhere, with high quality materials, many designs to choose from, and smooth one hand opening on a very safe slipjoint. I bought a Foilage green G-10 UKPK before I came to England for my latest assignment, and have since picked up a Spyderco Squeak and have a Spyderco Bob Terzuola on order.
The original purchase was just so I could have a UK legal EDC carry, but after carrying one for 6 months, I have come to realize that I don't need a lock on a knife for EDC tasks, and in fact most of the times locks just get in the way (with the possible exception of the axis lock, it is only a hair slower to close). Yet, I still get the easy opening and more safety than a standard traditional. It really is a perfect blend of modern design with traditional class.
And if I do run into a situation where I need a heavier duty knife, I just bring my Izula and a good explanation for why I need to carry it for the task.
(I do still like locking knives, but these really opened my eyes to a much wider world of knives).