I kinda like it all. Two hand opening is great, I got a number of beautiful knives that don’t even pretend to be one hand knives. Though if given the choice I prefer one handed opening.
Flipper: Very easy to use, when I got my first flipper only knife I found my self going for a thumb stud that wasn’t there. Now I find my self picking up my knives without flippers and reaching for a flipper that isn’t there.
Thumb studs: I prefer these for my Axis lock knives and my AO knives, for some reason it just seems to work best. I don’t know why.
Blade holes: Love em. Spyderco got me hooked on them Easy to use when I got gloves on.
I don’t know what I like best, I like em all and cant really decide. That’s why I need more of all of them.