GTX 970 its not good to buy on this time. You should go for an GTX 1060 because Its low on price, low on Power(Watts), low on heat AND more performance.
i will explain you the main differences between the different GPU brand models. For an example take PALIT GeForce® GTX 1060 Dual then its not a OC version. PALIT GeForce® GTX 1060 Super JetStream is a OC Version and it has LED glow feature and dual bios features. It more price than PALIT GeForce® GTX 1060 Dual.
OC mean Overclocked it can give a boost to the GPU Graphics Clock over than reference card. For an Example GTX 1060 reference card have 1708Mhz Boost Clock and PALIT GeForce® GTX 1060 Super JetStream have 1847MHz and also Gigabyte GeForce® GTX 1060 G1 have 1847 MHz.
OC...