I was originally going to buy a 480 for reduced power consumption and updated features, but I had a deadline and they were hard to find. This lead to realizing some Fury cards had been selling for under $300. I was looking at a nitro+ 480 too and those are around $270, plus the tax and shipping it came out to over $300.
The overclocked 480 cards were also using close to Fury power - guessing vega will be much more efficient based on this (HBM2 will help).
Ended up with a Strix R9 Fury (used). Turns out it can be unlocked. I could unlock 4096 full fury X cores, but with artifacts. Currently it does 3840 shaders without issue. Someone suggested turning up the voltage to see if 4096 is stable, but would defeat the purpose.
Power consumption was around 300W - 350W with the original 56 CUs (this includes the monitor that uses upwards of 30W and voltage regulator inefficiency), 310-380W with the 3840 shaders. undervolting is shaky but -30mW works most of the time. What I like is I can undervolt like crazy and see no immediate issues. On the 290x I sold and previous one, undervolting too far immediately results in artifacts and craziness. It also seems to be stable while in 3D mode with crazy low voltage. Most crashing happens while game is loading for some reason. If I lowered voltage while in 3D i bet it would not crash as easily with really low voltage. I haven't tried to OC, can't bother yet.
As it is the system uses less power than the 290x allowed previously, with higher performance. Turning on a second monitor barely adds to the idle watts unlike the 290x. While not gaming, the system without monitor is usually under 70W.
Which brings up the point, if AMD could set their voltage lower across the board, their efficiency would not look bad at all. This fury is probably really close to 980 power consumption. I could literally get the whole system without monitor to be around 250W.
tl;dr a good price on fury is probably a good alternative to getting a 480. 980tis are an option as well. I am not sure I would be happy with a 480 if I later realized those options were there. Newegg had new sapphire nitro fury cards available for $275 with promo at one point.