Which GTX 1070 is the best?

All 5 GPUs will perform in the same range in terms of graphics power as they are all GTX 1070 (same chips). Reason for the differences in pricing is the differences in factory-set clock speeds and features:

Out-of-the-Box Clock Speeds (Base-Boost):
G1: 1594MHz-1784MHz | Gaming X: 1582MHz-1771MHz | Armor OC: 1556MHz-1746MHz | Phoenix: 1506MHz-1683MHz | Mini: 1518MHz-1708MHz
*Phoenix is the non-GLH and non-GS version

OC-Mode (Auto) Feature:
G1: 1620MHz-1822MHz | Gaming X: 1607MHz-1797MHz | Armor OC: Manual | Phoenix: Manual | Mini: Manual

Cooling (Fans + Heatpipes):
G1: 3x + 2x | Gaming X: 2x + 5x | Armor OC: 2x + 3x | Phoenix: 2x + 3x | Mini: 2x + 2x

Power Phases:
G1: 8x | Gaming X: 10x | Armor OC: 8x | Phoenix: 8x | Mini: 6x

Power Delivery / Power Connectors Required:
G1: 1x 8-pin | Gaming X: 1x 8-pin + 1x 6-pin | Armor OC: 1x 8-pin | Phoenix: 1x 8-pin | Mini: 1x 8-pin

Backplate:
G1: Yes | Gaming X: Yes | Armor OC: None | Phoenix: Yes | Mini: None

LED / RGB Lighting:
G1: RGB | Gaming X: RGB (Nameplate only) | Armor OC: None | Phoenix: LED | Mini: None

So among the 5 GPUs, the one that stands out is the MSI GTX 1070 Gaming X for its high factory-set clock speed, Auto OC-Mode setting, good cooling performance, high number of power phases and delivery, and backplate + RGB lighting.

On another important note:
It is highly recommended that you upgrade your current entry-level Corsair VS550 PSU to a higher quality and more reliable PSU for powering your high-end GPU (esp. if you wish to OC).

These are some highly-recommended great quality PSUs you can take a closer look at:

SeaSonic - G 550W 80+ Gold Certified Semi-Modular ATX Power Supply ($56.89 @ Newegg)
EVGA - SuperNOVA G3 550W 80+ Gold Certified Fully-Modular ATX Power Supply ($60.98 @ Newegg)
EVGA - SuperNOVA G2 550W 80+ Gold Certified Fully-Modular ATX Power Supply ($79.89 @ OutletPC)
Corsair - RMx 550W 80+ Gold Certified Fully-Modular ATX Power Supply ($89.99 @ Newegg)

On another suggested GPU:
Considering that you are willing to spend ~$500 to ~$600 on a GTX 1070, I also highly suggest for you to consider the GTX 1080 instead. Prices of the GTX 1070 are still high as of this date, and you can get a more powerful GTX 1080 for the same price range:

Gigabyte - GeForce GTX 1080 8GB WINDFORCE OC 8G Video Card ($499.99 @ Newegg)

The above suggested GTX 1080 (Gigabyte Windforce OC) is currently priced the same as the GTX 1070 Armor OC you were considering. A GTX 1080 is ~30% faster in effective graphic performance compared to the GTX 1070 (http://gpu.userbenchmark.com/Compare/Nvidia-GTX-1080-vs-Nvidia-GTX-1070/3603vs3609).

The Gigabyte GTX 1080 Windforce OC model has a base-boost clock speeds of 1632MHz-1771MHz, an auto OC-mode speeds of 1657MHz-1797MHz, 3x fans + 3x heatpipes, 10x power phases, and has a backplate (but no RGB lighting). The $500 price range is $60 less than the MSI GTX 1070 Gaming X.

Another suggested model, at the same price as the most expensive GTX 1070 in your list, is this:

Asus - GeForce GTX 1080 8GB ROG STRIX Video Card ($578.89 @ B&H)

The Asus ROG Strix GTX 1080 A8G Gaming model has a base-boost clock speeds of 1670MHz-1809MHz, an auto OC-mode speeds of 1695MHz-1835MHz, 3x fans + 5x heatpipes, 10x power phases, has a backplate and has RGB lighting.

Getting the GTX 1080 for the same price as the GTX 1070 is definitely a better value purchase. Whichever GPU you choose, the suggested high-quality ~550W PSU is still recommended.