Caveat: Have not shot the AX. Just shot an AX chassis rifle. I have shot my AW thousands of times.
Reasons in favor of the AW:
1) You get more foregrip space with the AW. The AX will have a smaller foregrip, and then it turns into the tubular rail. It is a comfortable diameter for grabbing, but I prefer having a Plain Jane foregrip myself. But, it's a personal thing.
What do you mean you get more space with the AW? The AX has 360 degrees for 12" or more. There are much more "space" on the AX.
2) You can swap skins between the thumbhole and pistol grip on the AW which you can't do on the AX from my understanding. I prefer the thumbhole personally after trying both. Other people swear by a pistol grip. The AW you can try both to see what is best. Each person will be different.
The dimensions are virtually the same and feel very similar. Also, I believe AI is talking about offering back halves in thumb hole. I haven't tried it, but I'd imagine AI AW back halves would fit the AX.
3) The AW mounts the scope lower. I like having a lower mount on rifles because the cheek weld is more stable, center of gravity is lower, and recoil impulse is sent straight back which makes it better controlled for me.
The stability of the cheek weld is the same. Higher doesn't make it less stable. The stock is adjustable. You're right, the scope is higher and that can make it top heavy, but at the same time, the whole rifle is lower to the ground when using a bipod because the tube sits closer to the bore. Having owned both styles, the AX is more stable for the placement of the bipod.
4) The AW has an integral spigot mount in the chassis. You won't need to buy a mounting plate to use a spigot bipod.
There is no need for the spigot anymore. The AX comes with rails that can be placed where needed and mounted directly to the keymod tube. They have eliminated an item, thus offering a simpler solution to bipod mounting.
5) The AW has a non-adjustable trigger shoe. For a field rifle, I actually prefer the simplicity of a fixed trigger and knowing it can't move around on me by accident. Less things to go wrong. However, someone did contact AINA and they said the AX trigger assembly could fit the AW if you wanted to spend the bucks.
If you've used it, you'll see it isn't going to move around by accident. Its quite hard to move from the factory. But it does offer the ability to adjust it to the shooter for better trigger control. If something happens to your rifle that causes your trigger shoe to move, you've got bigger problems than the trigger.
6) The AW has straight insert magazines and magazine well (The AX chassis I tried used more of a rock and lock motion with the new mag well).
The AX has a cutaway that allows easier loading from prone. But, you can still shove them straight in.
7) I think the AW has a very distinct look that is a modern classic in the world of firearms. Again, totally subjective.
As Graham said, you'll just have to try both if you can. I tried the AX chassis rifle and decided I liked the AW more when the final tally was made. But, each person is different and again it was not a full AX rifle. The above though are features outside of chassis fit that you may want to consider.
I think were you to try an actual AX rifle and leave behind the spigot idea (one more thing to go wrong, right
), you'd end up realizing the AX rifle is superior and more refined than the AW, especially considering you don't have to add hardware to use things like night vision, QD slings, Atlas bipods, etc.