Oh, i just thought of another reason i dont like AO. This may only relate to the W&S guys, but you cant baton with the knife partly disengaged. its either open or close, no inbetween.
Not that I would ever baton with a folder, that"s what fixed blades are for IMO, but if you needed to, you could do so with any folder from Kershaw, including these:

These were just a few of my AO's that I had handy. As you can see, neither all the way open or closed. If necessary, I can take a few pics with them 2/3 or 9/10ths open or whatever. I have both AO and non-AO knives, bought them for functionality, looks, and sometimes price, all from my point of view. I see the AO as an added bonus, and would neither make or break my decision to purchase a knife if it did or did not have it.
I´m not old enough to need assistance in opening my folders. By the way, obviously neither is Paul (The Deacon).
A Flipper works best with an AO and limits the lock option to liner lock (except for the pass-through lockbar from SOG). For my liking that narrows down the options too much.
JB
In the picture above, only 3 of the six knives are liner locks. One is a stud lock, 2 are frame locks (one is even a titanium framelock). Still think your options are narrow?

I disagree with your flipper opinion also. In fact, I think it is best without an AO to complement it. Check out a Lahar or a Junkyard Dog II. Very easy to open with just the flipper.
I also love the Spydercos I own as well, my current favourites right now being my Millie in BG-42 and my Mini Manix. Both well designed in their own right.
Rik