My first auto was back in the 60's, a small, two-bladed, one small, one a bit larger, pen-type knife with each blade having its own button. Other than the buttons, looked like your typical pocket knife every kid carried.
Soon after that, it was an orange-handled, Vietnam era pilots knife, with a push button for the main blade, and a sharpened hook that opened with a fingernail that my dad gave me.
From then on, it was everything and anything I could lay my hands on that opened with a button or a flick of the wrist.
Went through a "Fallschirmjäger" gravity knife stage for a number of years. Had both the WWII era wood-handled knife, and a couple of later, green plastic handled issue knives, as well as a number of the commercial versions. The commercial versions actually work a little better for a daily use knife as the blade is a little shorter and better suited for that.
Had a bunch of the junk OTF's and a couple of the Benchmade Infidels too. Some of the cheap ones were actually pretty decent too. The Benchmades, meh, like a lot of their knives, way overpriced for what they are. I have a couple of their side openers as well, and their Butterflies too, and they work OK, but Ive had cheaper that were just as good, if not better, and more likely to actually be used (and abused) and no hearts broken when they get lost or beat up.
One of the best side openers Ive had and really like is the Spyderco Autonomy. Kind of reminds me of that old pilots knife I had, just better made and with a more useful blade.
Ive had a bunch of the Bokers (mostly the Kalashnikovs) as well, and used and abused a couple as my daily work EDC. They are/were inexpensive, but actually held up well to hard use, and took a decent edge pretty easily. I took the sliding safeties off of them and paid for that a couple of times when they opened in my pocket. Still, preferred them ready when I needed them than fumbling for that slider.
These days, Im carrying one of Bokers Butterflies for my EDC. Compared to my Benchmades, they are very reasonably priced (about $80), and actually have a smoother action and better weight/ballance to them.
Some Fallschirmjäger's....
One of the Kalashnikov's
Spyderco Autonomy
Boker on top, Benchmade on the bottom....