Thumb Stud, Oval, Flipper, or ...?

[randomlooker]

Spyderhole, followed by nail nicks. I hate thumbstuds, and flippers just seem to exist to scare people.

 

[Aaron Pepperall]

I prefer flippers or spyder holes. I find the thumb studs get in the way for slicing, carving and sharpening. For everyday carry I like my Tenacious but if I need something that can be opened quickly I will go with my Boker Thunderbolt.