As far as I know they are the same design with the only real difference being the storage compartments on the ACS (which may provide a wider cheek weld). If you want a cheek weld and a storage compartment go with the ACS, if not, CTR.
Don't have either (yet) so I have nothing more than that, but I know that they both have the same locking device on them to tighten the stock onto the buffer tube and keep it from wobbling.
given that i've only compared the 2 side by side before buying, i chose the CTR, what i like about it: comfortable on the cheek, comfortable on the shoulder, locks up nice and tight on your desired length (none of that annoying wiggling) it takes the quick detach on the side for the sling, and it looks just plain awesome!
sorry i can't give a great comparison, but i can tell you i don't regret spending the extra on the CTR, i love it