A co-worker of mine had the titanium version of the X-Ray Vision. I'd never heard of the SOG brand before. The knife looked seriously impressive, based on the hardware and blade design, the matte finish steel with tanto inspired shape, plus the rapid deployment and retraction he demonstrated. He then handed it to me. It had a lighter heft to it than I expected, but it still felt substantial. I moved the blade out by pushing my thumb on the stud, swinging it into locked position. So smooth! I was immediately taken by it.
I'm not a blade aficionado, so I don't have experience with many different knife brands. But I've been to stores and tried a handful. They were nice, but that SOG X-Ray Vision still kept calling to me. I decided I'd get one with the Zytel handles (quite a bit cheaper). I liked it so much, I got a 2nd one.
So, my SOG collection right now: X-Ray Vision (x2). I do plan to try out a few other models too.