The driver situation has completely levelled out in the last 2 years. It's not an argument anymore.

I guess if OP was looking to keep if video card for 5+ years then the RX Vega 64 *might* the better investment since it could potentially evolve to have 1080 Ti level performance but that's only a hypothetical scenario where every game engine started copying the Northlight Engine used in Quantum Break's DX12 backend ... 

1080 is the safest bet all around right here and NOW! 

1070 for 1080p, 1080ti for 1440p.

Also what games are you even looking to play on PC that you can't already play on your PS4?. If it's games from 5 or more years ago, you won't need a 1080 at all.

Given the same relative games performance , i always go with the more efficient choice. Which has meant Nvidia...since pretty much the 580/6970 days forward.

I would wait a bit though to see how this falls releases respond to drivers. Lots of benchmarks atm are on older games on mature Pascal drivers, whereas the new AMD cards could yield favorable results in upcoming titles.

I'd tell you to wait for Vega to launch and see how it actually performs, and then decide which one you should get. After all, it launches in only 5 days. Of course, that's if you can wait and card prices don't change until then (which probably will because of miners, sadly).

Otherwise, get the 1080.

pros for the 1080:
- energy efficiency
- pretty silent 3rd party cooler
- mature drivers

pros for the Vega 64:
- probably a bit faster
- more potential for performance gains through driver updates
- mining power if you want to dabble in that

The power bill is one thing, increased heat and strain on the components another.

I'm going with the 1080 for now, mainly because of the power requirement of the Vega. If the Vega was 180w it would be a no brainer.

Should I risk gaming with a 295w gpu/90w cpu on a 500w psu?

You don't need to take the risk.

Go with the Geforce. Plus save cash on the power bill.

One thing to keep in mind is that... As Power Supply's age, their maximum wattage, efficiency rating etc' decline. So even if it worked fine today, in a year it may not.

Considering he is going from a Geforce 600 series GPU from 2012...

The Geforce 1080 is the superior choice over Vega 64. And this is coming from someone who only buys AMD.

1440P is not demanding enough to warrant the need for a Geforce 1080Ti.

A 1070 is still overkill for 1080P.

The problem is that we still don't know the real power draw of Vega 64, only what AMD said. Polaris 10, the RX 480, ended up using more power than what AMD said...

In any case, it will also depend on the rest of the hardware in you PC: what kind of RAM (nº of modules and capacity), nº of HDDs and fans, etc. Given that only you know that, you could try one of those PSU calculators sites to see how much headroom you do have. Here are a couple of them:

http://www.coolermaster.com/power-supply-calculator/

https://outervision.com/power-supply-calculator