So far the majority consensus is that the MSI Gaming 4G and Gigabyte G1 cards are the "best" 970 cards to pick up. The MSI has upgrade their power delivery system from the 4+1 stock setup (4 phase GPU 1 phase memory) to mil spec parts providing a 6+2 phase setup. This allows it to OC extremely well. The Gigabyte G1 also uses 6 phase GPU power, but I can not find if it kept the 1 phase memory arrangement. From card pictures it looks like they did. However, Gigabyte offers a higher stock OC than MSI, but has a very large cooler. It also has more outputs than many of the 970 cards. It has 3 display ports similar to the 980, rather than 1 on most 970s.
The ASUS STRIX card is a bit dissapointing for me. It has 6 phase GPU power, but stock memory. However, it's biggest downfall is the one 8 pin power connector that seems to limit the max boost speed you'll see. The EVGA cards are almost entirely stock, which is a huge disappointment. With other manufactures upgrading power delivery, they should have given us a little more for our money. The ACX 2.0 cooler is nice though on the FTW, but you are paying to much for that.
I am also unsure about the Zotac AMP cards. There is an Omega and Extreme version. I can't find much on these right now, but everyone seems to breeze right by them. They were late to the show and we are only seeing their upgraded offerings now, but from the few pictures I've seen they have upgraded their power delivery a lot and could potentially be a big contender. Another thing to note, I've never heard anyone complain about their cards failing. Though they don't come up in conversation much, but I would think if people were having issues. Just some food for thought.