The three best choices for GTX 970 are Asus Strix, MSI Gaming, and Gigabyte G1.
The Gigabyte G1 has great Spec's. It runs cool. It's GPU is binned for overclocking. It has a dual BIOS option. It has a back-plate. The "bad" is that the card is too long. At roughly 312mm or 12.3 inches long, it is incompatible with many computer cases (and some motherboard connectors).
The MSI spec's were selected as the best in several GTX 970 comparisons. It has an excellent cooler and is very quiet. It has no back-plate. Without a bracing or a back-plate, the board is prone to bending (possible problem down the line). Otherwise a good choice.
The Asus has great spec's. It has a great cooler. It has a back-plate. Like the MSI, the cooler remains off until around 60 C making it very quiet. Of the three, it has the best build reputation. It is roughly 10 inches long (about the same size as the MSI).
All three have had issues with coil whine & defective cards in the customer reviews. Normally I would have included EVGA, but they have significant problems with their cooler design.
Of the three GTX 970's, I chose the Asus. I should note that I had a defective card. But when it came down to picking a replacement, I decided to go with the Asus Strix GTX 970. I am currently waiting on the delivery.
My reasoning was like this. Yes, I had a defective card, but that is a typical chance with any of the manufacturers. The performance spec's are essentially the same for all of the factory overclocked GTX 970 models (great). Having seen the GTX 970, I know it is a large, heavy, graphics card. It does need the back-plate to help support the card (the Asus has one). The Gigabyte G1 would barely fit in my case, but it absolutely would severely block air flow in the case.
So that left me with the Asus GTX 970. It had great quiet cooling. It had great spec's. It had a back-plate. It fits my case well. And in my opinion of the three contenders, it has the best reputation and build quality. So I ordered it (again).