Well, there is no GPU listed when you say GTX ACX... So thats one down.
Between the other 2 they are both GTX 980ti cards. One has some overclock, and the other is not specified. Look at the clock speeds on the two cards. One will probably be a little bit higher than the other one. The one with the higher clock speed will most likely cost more than the slower one.
The difference in speed between the two cards will be fairly minimal. Lets say the slower card can run GTA V at 60 FPS. The second one might (maybe) be able to run it at 64 FPS. Now I am not saying they can run it at those FPS settings, I am simply saying that the frame rates will not be dramatically higher. So what you need to decide is if paying more for the higher clocked card is worth the money.
There is a chart on the page below where the performance of a GTX 980Ti is shown in 8 games, and one of those is GTA V. Take a look at that to get an idea of what the GTX 980Ti is capable of.
http://www.maximumpc.com/nvidia-geforce-gtx-980-ti-review/