I want to go back to AMD, but right now Nvidia has too many edges on them. AMD has price/performance and more user-friendly drivers. Nvidia has smaller form factors, lower power consumption, higher horsepower. I guess physX, but I'm not sure that's ever added any value at all. Their drivers are more featured and powerful, work better with most games (I suspect in part because more games are optimized for Nvidia than not), but damn they are a pain to use.
According to the devs from the now-defunct Adhesive Games, the studio that was making Hawken, they asked AMD and Nvidia for info and help in trying to optimize the game for the various chipsets.
Nvidia was apparently very helpful in this process. AMD, not so much (apathetic comes to mind). Granted, this was a few years ago from an indie dev, and AMD seems to be waking up as to the effect this was having on their market share and such, but it would seem that a lot of the damage is already done. Hopefully they can improve things sooner than later.
I've not yet looked into the r9 3xx series, but if they knock down the power consumption (and hopefully the size as well) I might seriously consider going back to AMD. I also would rather support them as a company than Nvidia. I often get the feeling that AMD is doing a lot to advance the tech, and nvidia comes along and uses their much larger market share and the "Steve Jobs effect" to muscle them out. AMD getting out of the game would be devastating to consumers.
I am amused. I remember when it was the 'Bill Gates/Microsoft effect' that would 'muscle' competition out of a given market when they entered it.
Anyway, from a quick google, leaked charts for the R9 390/390X are pointing to better performance than the 980 series, but non-trivial amounts of additional power draw, which seems to be AMD's biggest weak point.
And before anyone claims I'm a NV fan boy...
Competition is usually a very good thing for us end users. I really do hope that AMD is able to pull something really good out of their collective hats. Right now, NV still tends to be the preferred choice based on performance, compatibility (but damn, I wish they would fix their funky OpenCL stack so I can use it with Sony Vegas or Premier), power consumption and heat output, which are most of the main points I look at.
I really don't give a flying fsck over things like PhysX, but I do have to admit to a certain interest in the alleged VR 'extensions/hooks' that NV is putting into their cards now. If VR really takes off, they might have a serious advantage over the competition.