The reference cooler is actually pretty nice for the GTX980, however so far the Asus STRIX is looking pretty good. It's $10 above reference at $560 USD.
http://www.pcper.com/news/Graphics-Cards/ASUS-Announces-STRIX-GTX-980-and-STRIX-GTX-970
*There's a LOT more going on with Maxwell:
1) New anti-aliasing method which is more efficient called MFAA
2) HDMI 2.0 (for 4K HDMI)
3) H.265 encoder (roughly HALF the size of H.264 video)
4) better VR support, dynamic light plugin for future games called VXGI
PCPER has an awesome review and benchmarks:
http://www.pcper.com/reviews/Graphics-Cards/NVIDIA-GeForce-GTX-980-and-GTX-970-GM204-Review-Power-and-Efficiency
*In the FUTURE games will more efficiently use the Maxwell architecture so you'll see performance improve again. There's just no point in a GTX780 or GTX780Ti anymore unless you are grabbing another one fairly cheap to add a second card for SLI with your current setup.
The GTX970 at $329 for reference is the most amazing deal I've ever seen. The Asus STRIX version should be able to overclock to match a GTX780Ti as it already sits above a GTX780 on average and they've shown the card can overclock by up to 20% (though I wouldn't) which might add 10% or so more frames per second on average.
**SLI 2xGTX970 is where it gets really interesting.
If you get two cards for a total of $680 you'll get at least 80% the performance of a GTX980 (if no SLI support) and up to 50% or so higher performance than a GTX980 depending on the game (so between 80% and 150% the performance of a single GTX980 depending on how well SLI is supported). Assuming a $560 GTX980 then you're paying just over 20% of the price for that.
As well, for games that use hardware PHYSX it's often better to assign the second card specifically to that so even if a game doesn't support SLI you'll still get a boost. I still often recommend the 2nd card approach even when it is supported, or at least try BOTH methods (SLI or dedicated to PhysX) and look at both frame rates AND game smoothness.
For example, Batman Arkham Origins has a lot of PHYSX on the high setting so it's a prime candidate to try both ways.