The 3.5 GB thing is a non factor ... kind alike Fox News, they love to get mad about things of no substance
http://www.guru3d.com/news-story/middle-earth-shadow-of...
If you use cards outta the box.....
The 970 is faster at 1080p
The 290x is faster at 1440p
If you use cards w/ MSI Afterburner
The 970 is faster at 1080p
The 970 wins by the proverbial hair 1440p
Other things to consider:
Twin 970s require a bigger (250 watts extra) PSU
Twin 970s add 246 extra watts of heat to ya system
970 comes with Witcher 3
970 comes with PhysX, G-Sync and Shadowplay
The 970 has outsold all R9 + R7 cards combined so if you decide to add a 2nd card later on will be plenty in the channel.
Sapphire and MSI arethe two best 290x cards.
Gigabyte and MSI are the two best 970s.
The Gigabyte and MSI compete for best performance. Both routinely overclock well providing boost clocks over 1500 Mhz but the Giga wins more than it loses. Asus and EVGA have trouble breaking 1500.... with moist reviews around 1465. The Giga doesn't fit in many cases due to its 12.18" length and the Giga doesn't have the two its fans independently controlled. MSI shuts off its fans below 60C and will turn on one fan based upon GPU temps and the other based upon PCB readings.
If you want to see why the Asus and EVGA don't overclock as well read about the differences in VRM Phases, power delivery, chokes, capacitors, memory / VRM cooling in the article here. The nitty gritty is towards the bottom of the pages for each card (2-4). Not also that EVGA fixed the design defect noted in the article in the new SSC model so be careful as both are still in the channel. They also increased the number of VRM phases but not enough to match Giga / MSI.
http://www.bit-tech.net/hardware/graphics/2014/09/19/nv...