GIGABYTE RX 580 4GB vs MSI RX 580 GAMING X 4G

Solution
Get the Gigabyte. It doesn't make much of a difference if they're the same chipset (RX580).
Also, some simple math. 8GB VRAM > 4GB VRAM.
MSI GAMING X series are expensive, they look good but personal opinion, they should be cheaper.
For the price of MSI's 4GB RX580, you could get twice the VRAM that it has.

Well, conclusion. Pick any of these two ( or three ) choices won't affect much. GLHF!
Get the Gigabyte. It doesn't make much of a difference if they're the same chipset (RX580).
Also, some simple math. 8GB VRAM > 4GB VRAM.
MSI GAMING X series are expensive, they look good but personal opinion, they should be cheaper.
For the price of MSI's 4GB RX580, you could get twice the VRAM that it has.

Well, conclusion. Pick any of these two ( or three ) choices won't affect much. GLHF!
 
Solution
I went with the extra VRAM Sapphire 580 8GB Nitro+ LE:
GSzjzQY.jpg
 
That backplate really does wonders for the looks of the gpu since that's all you basically see anyways.

It's a Rx580. Performance wise they are all similar, either top line like the Gaming X or FTW or mediocre like the Armor 2 or SC. The bigger differences being price and overclocking. If you can get an 8Gb for roughly the same price as a 4Gb, it's well worth the difference. Don't know anyone who doesn't like a buy-1 get 1 free, so that kinda also applies to buy 4Gb, get 4Gb free.