Titan hands down. Nvidia stepped their game up and made the titan quieter, more power efficient than the 690 whille still giving out more permormance than the 690
Actually the 690 performs better than the Titan. However, the Titan is better in SLI, due to the fact that its only 2-3 GPU's up against the 4-6 GPU's of the 690 (690 is a dual GPU card). Scaling is better for Titans, but the GPU is really only worth it in SLI. The 690 gets my pick.