as i said AT THE MOMENT OF WRITING , stongest card providing HIGHER HASH RATE (no matter the power consumption) is RADEON PRO DUO ... 900 to 1100 hashes /s depending on the oc you apply ... of course the higher the hash rates the more inefficient it is... at 900 hashes is a bit less efficient than nvidia cards (4.5 w for each hash)
Per that number the TI only uses 156 w per hash?
The 1080 Ti can be set to do ~600 sols at ~150-155 watts. About 3.9 hash per watt ratio. You can get it up around 700 sols or higher but it will use the full 250 watts and beyond, making it very inefficient if you run it that way.