I play games like tomb raider & bioshock on the couch using an Xbox controller. I watch movies, YouTube, Netflix, Amazon prime on it when I'm not gaming. The Radeon 7850 I have is showing its age as I have to turn effects off more and more with each new games.
The real reasons to get a GTX 9 series are
HDMI 2.0 support
Lower power usage (save the environment. You can put a GTX 980Ti in an HTPC... it's an HTPC, not a low power computing unit. My next HTPC will have hopefully a Dual GPU chip in it for 4K gaming).
Some Decode for HEVC( ON the 960?)
For the HDMI 2.0 support, the adapter is now out for AMD, but if you don't own a 4K TV, then don't buy one.... get a 4K monitor instead. The 4K Korean Import monitors are where it's at. Just look over in the Display section for someone who just bought the Wasabi Mango. Great options, and you get Freesync in your TV for if you have an AMD GPU. If you don't, no harm, you can't get Gsync in a large screen monitor/TV anyway.
You have not mentioned a single thing so far though that would make me recommend a GTX 960/970. Other Radeon cards offered are far better options.
You really should go with as much power as you can afford. Just because you're at 1080p, doesn't mean you can't get better fidelity.
If you haven't played a game like Battlefield where it has a resolution scale, set it to 100%, then set it to 150% and if you like the difference, that's similar to what you can get with an R9 290 over a GTX 960 most of the time in games.
But I mean really, you have a TON of graphs in this thread. Just look at those. See if you'd rather be at a GTX 960 level, or a R9 290 level of performance.
Just realize that just because you're at 1080p doesn't mean you're at a limit of performance. Even a GTX 980Ti would still be beneficial due to extra features/DSR at 4K/etc. Every bit of performance on your card will be utilized no matter how fast of a card you get, so might as well get the best bang for your buck no matter what card that is.