I can get both for the same price (gtx 1080 will actually be cheaper). Early reports say gaming performance is about the same, but jumping from geforce 600 series will be a yuge jump either way. I'll be putting the gpu in a small itx case, I was seriously considering Vega the last few weeks, but then saw the power draw, 295w vs 1080's 180w. That is awful, I only have a 500w psu, it's a small case with a high end cpu like a 6700k. So now, I'm heavily leaning towards the 1080.

Go with the 1080, I'm not sure if your current PSU will be able to maintain the power draw and I'm not sure if your case has enough ventilation either ...

It's a load of bullshit having to wait for the games to catch up to the hardware plus 1080 has a moderate amount of overclocking headroom too if you want more performance for the future ...

For me I'll be looking for a 1080 Ti or maybe go with Volta ...

Geforce 1080 is a no brainer. It's more energy efficient. Unless of course there is an AMD-specific feature you want?

A high-quality 500w PSU could handle Vega just fine though. I must stress the *high quality* aspect.
However, you may not be running your PSU at it's optimal efficiency curve in such scenario's.

I must ask though... What resolution display you running? Might be better to drop down to a Geforce 1070 instead if it's only 1080P.

The PSU is really good (I think), Silverstone rated 80+ Gold.

Mainly on 1080p-1440p 60hz displays, I got a Oculus Rift as well, so no 4K or 120fps etc. I'd get a 1070 if I could find it cheap, but they're as expensive as the 1080 I'm looking to get. (KFA2 Exoc)

1080 since it will pay itself back by being much much much more power efficient. Its also better optimized since its been out for quite some time and Nvidia Drivers have proven better in many PC games in general.

But still you shouldn't risk it even with reference cards ... (650 watts is the safest bet and 750 is a safer bet if you want to overclock Vega) 

1080 is a safe bet for your system overall and there's no guarantee that Vega will outperform the 1080 future games ... 

1080 it is if you can't find the 1070 cheap.

1060 would be passable, but you will probably want more grunt than that for Oculus Rift.

PSU's these days have various protection mechanisms which makes it pretty much risk free.

You draw to much energy, it shuts off.

I used to run Dual Radeon 7970's (250w~), Phenom 2 x6 1090T (125w~) on a Corsair HX 620w without much drama.
I wasn't on the PSU's efficiency curve and I likely shortened it's potential life, but it was fine. (Didn't care with a 7~ year warranty.)

I did eventually upgrade to an 850w unit though.

Not only that. But there is the potential that by the time it *is* faster than the 1080... You will be looking to uprgade anyway.

That depends how much hours he spends a day gaming - if he spends a few hours or less, there will be almost no difference in power bills.

AMD cards always.... ALWAYs age better.
Id say get the RX Vega 64, if you can find it for the same price as a 1080.
Its supposed to be slightly faster too right?

Depends. If your on Windows, the GTX 1080 will be a better buy for gaming. If you also need it for compute intensive tasks, get the Vega 64.

If your on Linux, get the Vega 64 regardless.