GTX1070:
Not sure what the "rumor" comment above meant because we already know the GTX1070 details. It's been tested and is roughly 81% as fast as the GTX1080 (give or take 2% depending on the game).
Following applies to GTX1070 except benchmarks:
http://www.pcper.com/reviews/Graphics-Cards/GeForce-GTX-1080-8GB-Founders-Edition-Review-GP104-Brings-Pascal-Gamers
Review (for benchmarks, or just use 81% of GTX1080): http://www.gamespot.com/articles/nvidia-geforce-gtx-1070-review/1100-6440307/
Quick highlights (you can read more in the first link):
1. $400USD+ (non-reference)
2. similar to GTX980Ti/Titan X
3. 8GB VRAM
4. VR (Virtual Reality) boost up to 1.6X previous (needs the new hardware, and NVidia plugin for game/app)
5. better triple-monitor support ( read about SMP or Simultaneous Multi Projection):
6. HDR
7. HVENC
8. higher bandwidth video outputs (HDR, high refresh, and resolution add to bandwidth requirement)
9. Fast Sync (does support earlier NVidia cards)
10. audio (bounces off objects for more realistic audio... not sure if that's HDMI/DP output only or not)
11. Ansel (take 2D high-res and 3D snapshots of game... pretty neat I guess)
AMD Polaris:
We don't have any detailed info on that yet unfortunately. I WANT them to compete well against NVidia even though I will be buying a GTX1080.
The next year is really critical for AMD. They have some competitive CPU's, APU's and GPU's coming which hopefully helps to start digging them out of the RED. They've been so hurting for cash they made a deal with China and Samsung.
AMD's been investing a lot more in their DRIVERS, working on VR support (we don't know details yet) and generally trying to improve. So, kudos to them and I hope they can keep it up. I think AMD can stay afloat though. They also have a small amount of cash coming from the console APU's and Apple.