Z77 is pretty close to 87/97. Unless you had a low end board now, I would just grab the 3770k of you want to save money. If not, the 4590/4790k will be a good jump. 87/97 has more usb3 sata3, pcie 3 (needed for high end crossfire or 980/290x to prevent bottleneck.)
What board are you running...