The Griptilian based Ritter RSK-1 turned into a favorite of mine. For one, the action is exceedingly smooth and distinct. Its as smooth as most $5-600 customs out there imho. And, the Axis lock needs no introduction to ease of use, integrity and dependability. Even with it's plastic handle this knife just seems to fit the bill for a near perfect all around EDC knife.
The Kershaw Bump is another knife that grew on me and reached the "favorite" status. Once I purchased it, I began to appreciate it's attributes. The simplicity and effectiveness of it's frame-lock design, the lightweight character of Titanium which makes it easier to carry than one might at first think it would be, it's AO mechanism which seems right at home after a couple operations, and the the finely ground recurve blade that just seems to put the finishing touch on a knife that could pass muster on a custom table anyday.
There are several more that are knocking on the door of unexpected affection but, in order to limit the number I only mention the above two.