Currently, I'm knifeless. Apart from drawer dancers that I don't want to mess up, I have no knives to EDC.
One is out being worked on, and the other is in pieces on my desk, being tuned up.
On any give day I typically carry two Spyderco folding knives(in addition to whatever other stuff I carry) and despite whatever rotation I enforce, the primary EDC inevitably ends up being a lockback.
Lockback Pros?
-It requires no conscious thought to disengage, because it's the lock I'm most familiar with. I can unlock it in my sleep.
-Stays closed in my pocket better than other locks.
Lockback Cons?
-Can be slightly stiffer to open than other locks(but only just barely)
-Requires more hand adjustment to disengage the lock.
The secondary EDC is typicall a Dodo(Ball Bearing Lock)
BB Pros?
-Extremely easy to disengage, takes some getting used to, but there's not much learning curve, the action is intuitive after a day.
-Very smooth opening(flickable)
-Easier to maintain(lock mechanism is wide open, compressed air is all that's needed)
-I can see the lock working, and if something falls, I'll know exactly what it is.(see above about mechanism being wide open)
-Very fun to disassemble and play with(just don't lose the pieces)
BB Cons?
-On larger blades, they may be a little too flickable
-Some people find them hard to use, I find the opposite is true for me.
I HATE liner locks, for several reasons, and I tend to avoid Compression locks. They are easy to use left handed, but the act of disengaging the lock requires a different movement in each hand, and I like the action to be identical(like lockbacks and BB locks).