I know I'm late to the party, but I have some thoughts on the two...
KRG W3C - is a Sako TRG chassis for the Rem 700. It's all identical from rear end compatibility, grip angles, etc. So, you're basically asking Sako vs AI for ergos. You will receive no correct answer. It's all personal preference. KRG did a good job on their chassis, it's nice gear, not perfect, but very nice. I don't however think it's as "finished" as the AI AX. I'd certainly keep an eye on KRG though.
It interesting that some people willingly complain about thumbhole on AI's old chassis, but the Sako TRG folding and by extension KRG's rear gets a pass. Must be because it's just a very large thumbhole?
The New 2014 style AX looks good. But I'm not convinced that even 5% of the people that own them actually need top or side rails. I'd love to see AI keep the AX, lose the tube, extended their handguard out a little and bring in the new AT's NV rail.
Now, for the OP.... I'd run neither with a 30" barrel, because really I'd probably never run a 30" barrel
Seems to me that's a benchrest rifle and would probably be fine with a benchrest stock. Between the two asked about, 6 of one, 1/2 dozen of the other. See if you can get your hands on one.
Fwiw, I have some gripes on the W3C, I'd like to see a couple of things changed. But I think KRG has some real traction with their new Xray. Not for OP, not for 30" barrel (as it would be stupid front heavy), but in terms of marketing, and carving out a niche, I think they're on to something. Esp when you consider a B&C, and bottom metal, is practically the same price as the XRay chasis, that's a no brainer.