Hmm....it is either Nvidia GTX970 3.5GB or AMD R9 390.
Dont get AMD 380. It is an old design
without any support for better Powertune/ZeroCore and Variable Refresh Rate support.
R9 390 = Better idle power management than 380 (use more power than gtx970), 8gb of VRAM (sure can put a lot of gta V and battlefield texture cache), support for Freesync.
GTX 970 = overclocking beast with 3.5gb vram, support for Gsync. 8bit HEVC support in hybrid DXVA.
In case if you plan to purchase monitor with variable refresh rate in future, you need to make the choice for either freesync or gsync video card now.
I can see you are the type that purchase an expensive goods for long term usage. So, choose which variable refresh rate(VRR) video card to match with your future VRR capable monitor.
Thanks for the input. Which is the lowest idle power? I don't oc my PC unfortunately as my glory days has passed. BTW does nvidia card support for audio output via hdmi because I'm using home theatre system for audio? I'm bit noob when it come to green team.