Lockback/ Triad lockback
Compression lock
Frame lock ( as Spyderco does it on CPM M4 Millie, and Tuff with the steel insert. It's better than carburizing IMO.)
Next= Liner locks
Lastly= Benchmades Axis lock. I'm loving it on some like the contego and D2 Becker(?). Some of the smaller knives leave me underwhelmed with the Axis for some reason. IMO, the Contego CPM M4 at RC 62-64 is one of the best knives released in the last 2 years. Another is the M390 805 Axis lock. It has less recurve and is easier to sharpen than a 710, which I like everything about except the recurve. I freehand sharpen and that's why recurves annoy me.
Liner locks can be anything from dangerous to use junk to stronger than most framelocks and smoother like the Spyderco G.Bradley, and the Vallotten sub hilt.
Still, I grew up with the lockback being the one to get if you could afford it and if built well like Spyderco, and Cold Steel ( including, or maybe especially the triad) it will always be my favorite. AS a personal note I have carried a Spyderco Endura of one generation or another since 92. All are still intact and EDC'able. They don't wear out, they just get smoother.
I in no way am suggesting it's the best, or even it works for everybody. Just my opinion about it. The Triad is a bit rough, but strong, and resists loosening well. People who don't like the force needed to clost should reconsider buying, though not out of any QC or design problems. It's just tough, with a long travel to close and needs a strong thumb and decent sized hand ( mine are XXXL)
Joe