I've used all four (SE, LE, CG, Skinny--five if you count both the flat and mag grip CG) and I like them all for different applications.
SE is pretty much an LE with flat/ribbed G10 grips and double-cut finish. Being slender in the grip it's the easiest/least bulky carry and slides smoothly into tight places like the console of my truck, without giving up a lot in hand-filling feel due to the "belly" in the grip design of the SH1.
LE feels a little better in hand to me in terms of control--even with medium-size hands and stubby fingers, I like the mag grip design best with the "bulges" for security, the smooth outer contours for chopping and the inner ribbed-dished-out areas for traction. In fact, the ASH1 mag handle is one of my favorite handle designs overall. As a cutter, the full flat grind and satin finish make for smooth slicing and the point is the slimmest for penetration/fine point work. For me, the satin finish is easier to keep clean than the double-cut, which tends to discolor quickly. Over all, I like the LE in hand and for use better than the SE and I'd have to say, the LE would be my choice overall if I were going to keep just one style.
Skinny weighs about the same as the LE, which surprised me. Apparently, the trade-off is that there is actually a little more steel volume-wise in the Skinny blade due to the convex grind, because the blade is thicker down almost at mid-blade where the grind starts, than on the LE which begins tapering from the spine. Obviously, there is less steel volume in the Skinny handle due to the thinner stock, and the proof of that is to lay all the different ASH1 models on a table. The LE, as well as the SE and CG, all balance on the handle with the blade point off the table. The Skinny will tip over and rest on its point.
The Skinny has a little better chopping balance because of its slight blade-heaviness and is a great, great batoner for that length blade. Not quite as smooth a slicer IMO as the LE, but that's partially because of the difference in finish. For the money, I think the Skinny is the best deal by far, dollar-for-dollar.
I've had both the flat and magnum grip CG, and have not used either much due to the significant weight of a full-tang, .32" thick knife. I got rid of three CG's and retained one for emergency use only, as an intrusion/escape/rescue blade for carry in an automobile if I don't have room for something bigger like a NMFBM. The balance is really not bad at all--basically the same balance as on the LE and SE, just much, much heavier. And I think the mags on the CG feel good in hand. But so much weight in such a short knife means it can't compete with a longer knife of the same weight in chopping, and supporting that much weight is very tedious on fine tasks, IMO. The CG truly is a sharpened prybar. As such it would be indestructible to wedge or pry with, or pound through hard material, but it's just a huge chunk of steel to try and use for most chores you'd want a knife for and is prohibitively heavy for belt carry--actually weighs more than some of my firearms.