I don't like flippers, they scare me. I have almost cut myself with them, numerous times, because they were flippers.
I think the Spyderco Trademark Round Hole is the best, most intuitive, elegant, effective, least likely to get in the way, can't hang up on your clothing. {And if you are smart, and buy a Spyderco, you will be doing business with one of the most innovative and classy companies out there, period}
The others are OK, they work, but I don't prefer them.
But, sometimes, other things make the decision for you.
I am a HUGE Spyderco fan. But, I EDC two BM Rukus. I love the knife, can't help it, they are like old friends, it would hurt me too deeply to part with them.
My Spyderco love mostly expresses itself in the fixed blade. Ah, so good.