It's not that I always flick open thumb stud folders for the sake of flicking them, it's just that every time I am opening a thumb stud via constant manual pressure I wish that it was a thumbhole and within the week one of my Spydies is in my pocket again. And most thumb stud knives I have owned have been Cold Steels, which are always begging to be flicked and stuff with their awesome locks and heavy blades.
Of all the blades mentioned...
I'm currently EDCing a Spyderco Manix 2 Lightweight. Made in USA, caged ball lock that functions a lot like an Axis lock. It's light enough you could wear it in dress pants, but is still ergonomic, full sized, and strong. Runs about $75 though.
I really like it so far, it was a thoughtful Christmas gift.
Since I got into knives about a year and a half ago, the last 5 months, and 3 months some time prior to that, I've carried a Spyderco Endura, either plain edged FFG or combo edge. I really, really like these. Thin, comfortable, excellent cutting blades with a really good steel. I really like the lockback too.
I've owned a byrd Cara Cara 2 in both G10 and FRN. The FRN model is a little cheaper, but I would very very highly recommend the G10 model. It was a pretty classy knife, and it gives you something different from the Endura, whereas the FRN model is pretty much a cheaper Endura FFG. If money is tight and you are cool with touching up the 8cr13mov, they are good knives.
I carried a Cold Steel Voyager for all of 3 days- felt awesome in hand, and that 4" stonewashed clip point was beautiful, but way, way too thick for my pockets, and the texture on the handles destroyed my pants. Literally ripped open the pocket of a pair of Wranglers in 3 days. It didn't have s smooth portion of the handle for the clip like a Spyderco... The knife was impossible to get out of my pocket quickly due to the thickness and size. YMMV. I traded it for a Spyderco.
I've also carried a Mackinac Hunter, Recon 1, American Lawman, and AK-47. They are all a little thinner than the Voyager, and I really liked each of them for their own little perks. However, the thumbstuds and pants shredding G10 (and especially the Wave on the AK) soon led to more Spydercos. One Cold Steel I haven't tried that really appeals to me is the new Code 4. Super thin aluminum handles. Thin and pocket friendly, but still has a 3.5" blade and Triad lock. The Triad lock alone is a good reason to try a Cold Steel.
But that's enough rambling about knives at 1 am...