I would put the performance/dollar value of the 770/780 Ti about the same as a Titan. The difference is going to show up in your needs -- amount of VRAM, power requirements, slots available, etc.
With the hardware I have, the Titans made the most sense (heck, the 780Ti hadn't even come out when I had to buy). Today, if I were provisioning a different workstation, I might very well have picked something else.
