Spyderco's liner locks and compression locks are always easiest to open for me.
The Spyderco Resilience, although it's a 4 1/4" blade, so a little bigger than your specified range.
The Military is fantastic, though I had to finally admit to myself its just not my type of knife. And when squeezing tight, I could get a little blade wiggle due to compression on the liner lock bar.
The Caribbean, right in your range, is very easy to open. Maybe too easy. I adjusted the detent strength on mine. And closing it can be a bit of a chore, because of where the standoff is positioned; it's far enough back that when you pinch the knife to actuate the lock, you squeeze the scales just enough to sandwich the knife's tang, and add friction, meaning unless you loosen the pivot to the point of blade play, you won't really be able to consistently swing the knife closed in one smooth motion, but it will always stop short. If you are a tinkerer and want to install another standoff, then you can fix that problem so that you have a no-blade-play lockup,
and a drop/swing shut closing action. I didn't do it, and instead sold my Caribbean at a loss.
The Manix is a great knife, and I sometimes wish I had kept mine, too. That ball bearing lock! But I'm a tip down guy now, so it's a no go anymo.
The Yojimbo was great for opening, possibly the best compression lock implementation I've ever experienced, and certainly worlds above the Shaman or Caribbean for ease and enjoyment of use.
I have a Yojumbo on the way, and I'm hoping it will match or exceed the Yojimbo's lock quality.
The Endura 4 and Pacific Salt both had fantastic action as far as lockback knives go, but I sold mine. I have a Pacific Salt 2 yellow plainedge on the way that will fill the role of both of them.
the full size Military which I never managed to master one handed opening with a zip tie, or the Spydie drop, nor the middle finger flicking technique.
This is strange to me. The Military is a tip down only knife, so I don't see the point of putting a zip tie on it, unless you simply kept it clipless and tip up in your pocket?
Tip down knives should be carried in a back pocket, in order to be able to access and open them comfortably and efficiently. A side pocket doesn't work as well, though if you don't mind putting the knife in the middle of your pocket, and mot all the way back, I'm sure you can get it to work.
I've never been a fan of the middle finger flick. I never knew how to do it for the longest time, but then I learned it just to see what I was missing, and I tried to like it for a little while thereafter, and practiced it with all or most of my Spydies. In the end, I came to the conclusion that the middle finger flick is just not worth it. Index finger flicking makes a lot more sense to me, because it can be done more consistently, and more importantly, doesn't require taking your fingers off of the knife's handle like middle finger flicking does. Middle finger flick is asking to drop the knife, but with the index finger flick you can firmly grip the scale with your pinky, ring, and middle finger as you flick, making it a much more secure grip to open your knife with. I open my knives with the index finger flick, which I feel is the most intuitive, as my knife opens and points exactly where I am pointing - with my pointer finger. You can't get any simpler than that for muscle memory. But I also use the thumb roll and thumb flick, depending on... how I feel, I guess. Those methods are also very easy.
The ones with zip tie wave mods ! 
