Sapphire R9 270X 4 Gb or Sapphire Toxic R9 270X 2 Gb?

Solution
If the 2GB version is $50 less than the 4GB version then get it. If the 4GB version is only $10-$30 more then might as well spend a little extra and get it.
Modern games and applications are requiring alot of VRAM, so in theory the 4GB will be more future-proof, but as dovah said, depends on the price, an abusive higher price is a bad deal.
 
If you haven't bought the i7 yet then I would just save your money and use the extra $100 and get an R9 285 or the R9 290. An i5 4440 or the 4690K at the most are the best price/performance ratio components for gaming. Unless you do a lot of video editing and such then you don't need the extra threads and 2MB of L2 cache that the i7 has over the i5 (which doesn't make a difference in a ton of games).
 
I will not buy a R9 280 or R9 290. I will buy a sapphire R9 270X. So 4 GB will be better, I suppose. I have old core 2 duo E8400 with GB ram and Asus EAH HD 4650 1 GB DDR2. I cannot play games as I wish. I do not think R9 270X is a bad card at all.