Which 7950, Giga, Saph, Or MSI?

This was also posted in the general graphics card forum, but I wanted more Radeons peoples view.
SAPPHIRE Vapor-X
http://www.newegg.com/Product/Prod [...] 6814202003

MSI R7950 Twin Frozr
http://www.newegg.com/Product/Prod [...] 6814127667

GIGABYTE GV-R795WF3-3GD Radeon HD 7950
http://www.newegg.com/Product/Prod [...] 6814125414

Money isn't an issue between these cards really, I am putting this all in:

Case Antec Three Hundred Illusion
CPU Intel Core i5-3570K $220.00
Cooling Fan COOLER MASTER Hyper 212
MotherBoard GIGABYTE GA-Z77x-UD3H
Memory G.Skill Sniper 1866
GPU ?????
PSU CORSAIR CX Series CX650 650W Power Supply
Hard Drive Seagate Barracuda ST1000DM003
Operating System Windows 7 Home OEM


Anyone out there, should I upgrade to a 7970? I just don't see the value, I do plan to overclock. Also, should I scrap my Radeon love and just do a 670? Many thanks guys, I am sold on the 7950, but if you honestly think a 7970's bigger bill is worth it (hope not) or an equivalent on price and performance Nvidia card is out there, let me know. Thanks again!