Wow I will have to think hard. I am a big time folding knife collector and have easily over 50 of them.
While I rotate some here and there, I have some definite favorites.
My best Every-Day-Carry is a discontinued model called CRKT BladeLock by Michael Walker. It's a 3.5 inch otherwise simple folder with a unique feature. It's thumb-stud is the lock, and it locks in its open and closed position. You press the stud into the blade and push. It's easier than it sounds and I can open it faster than most people can do regular folders. Because it locks shut, the pivot is quite smooth and opens very easily once unlocked. Just a great action on it, I've had it for over a decade and it works fine.
Also the unique lock actually saved me once. Because it is rather uncommon for a folder to lock shut, most people who pick it up cannot figure out how it works. I used to carry the knife clipped to my back pants pocket, and one time this jerk came up behind me and yanked it out, intending to use it against me. But he couldn't get it to open due to the lock, which gave me time to hit him pretty hard, regain my knife and scare him off with it.
When I am at work, I have to keep any knife I carry under 2.5 inches, so I added the Benchmite II to my collection. It's tiny but very well made, and also locks closed with a "levitation lock." I work with children and sometimes people of unsound mind, and while I normally make sure to keep it out of sight, you never know and it's good to know it would probably prevent most people from opening it. Besides, it's a Benchmade, one of the best brands out there. It has a lifetime warranty and sharpening service.
Just a handful of others worth mentioning are my SOG Pentagon Elite II, the full sized Applegate-Fairbairn combat folder (these two are my biggest), the CRKT Pharaoh which just looks really cool, and I also have a Cold Steel Ti-Lite in Zytel (cheaper) because I it's just like my father and grandfather's stilettos (they are both Italian).