-Hands down best I’ve got or ever tried is my Smock SK23! (Waiting for Spyderco’s version...)
-Best big company production knife, Spyderco Domino, ZT 452 not far behind (it’s smoother overall but although I love the strong detent, it’s just quite right with the position of the flipper tab for me).
-Brous Bionic Xl gets honourable mention. The flipping action is just about perfect but I felt the need to mod the flipper tab to make it smaller and add a finger choil at the same time. (Clip was terrible switching to left carry).
-My SteelWill Cutjack is great right handed but alas only o.k. Lefthanded. I guess the way pressure gets applied to the fairly flexible handle messes up the lock bar pressure making the action far less reliable.