GPU upgrade

Hey there I am wondering if some of you guys could suggest me some graphic cards... I don't want to spend more than 700.- Swissfranks what is equivalent to about the price of a GTX 780... i thought about that card but I wonder if there are some good alternatives for not more money...

My current specs are

 Asus Sabertooth X 77 Motherboard
 Intel i7 3770k CPU (not overclocked)
 16GB RAM Kingston Hyper X Beast
 Corsair AX 850 Power supply
and SSD drives etc...

My current GPU is a GTX 570 overclocked to 860 MHz Coreclock and 1720 MHz Shaderclock

Thank you in advance.
  

Yeah, get a GTX 780 or a R9 290X. Wait for the reviews that should not be far away. (NDA lifting date not yet revealed, but perhaps already this coming week.)