Ok then 2gb it is no doubt about it 4sure
Were 2 buy which is the best (Also Company's)
Sapphire/MSI/Powercolor AMD Radeon HD 6950 2 GB GDDR5
OR
MSI/Zotac/Asus GTX560Ti 2GB DDR5
GTX560Ti 2GB DDR5 has a bit more clock speed and DDR5 speed & less power usage
Between both of them which has a better updates & supports for future
OPTION 1
1) If you're planning to buy to 2GB version of HD6950.I will suggest either go with MSI or Sapphire.*www.msi.com/product/vga/R6950-Twin-Frozr-III-Power-Edition-OC.html
2)If you couldn't find the above suggested Graphics then next option will be
MSI N560GTX-Ti Twin Frozr II 2GD5/OC. Which is a overclocked version of nVidia 560Ti chip, its clocked at 880 MHz and Memory clocked at 4008Mhz.I have the same graphics card, only difference is i have the 1GB version with me.
P.S-Always higher core and memory speed doesn't mean that its powerful.In stock speed AMD HD6950 is more faster than nVdia GTX560Ti.But a overclocked nVidia GTX560Ti will give tough competition to AMD HD6950.
OPTION 2
If you're looking for 1GB version of AMD HD6950 or Nvidia GTX560Ti.
Then look no further and get
MSI GTX560Ti Hawk.Its super clocked edition.The core speed is 950MHz and Memory clock runs at 4200Mhz.And another thing it has MSI Twin Frozer III cooler, its terrific cooler.You can even overclocked the Hawk to 1000Mhz core speed without any overheating problem.
Check some review of MSI N560GTX-Ti Hawk
MSI N560GTX-Ti Hawk Review - Overclockers Club
MSI N560GTX Ti Hawk Video Card | MSI N560GTX Ti Hawk,GeForce GTX 560,Video Card,Benchmarks,Performance,Reviews,Steven Iglesias-Hearst,MSI N560GTX Ti Hawk Video Card Benchmark Performance Review by Steven Iglesias-Hearst
MSI GeForce GTX 560 Ti HAWK review
HARDOCP - Introduction - MSI N560GTX-Ti Hawk Video Card Review