I would recommend the two MSI 770 GTXs. You don't the absolute top of the line right when it comes out, when it will become less expensive fast when the next one comes out. The MSI 770s get very, very good cooling compared to any other setup on the 770s. Plus, you have 2 GPUs, which will give you 1GB more of GPU memory total than the 780, and will help spread the workload of 2+ monitors. The 770 is also faster than the 780. In my personal opinion, the two 770s would be the best choice for performance and bang for your buck.
Hope this helps.