the difference is mainly the hardware used. For example, simple TI from EVGA dont have the same cooling system as the FTW3 .
So you can O/C more depending the model you have. In my opinion, the ASUS cards are too expensive for what they offer
My Asus 1080 Ti Strix Gaming 11GB was 900 euros. If the bitcoin will keep todays value and diff (of the altcoins) will not increase the next months, I will reach ROI for my GPU in 112,5 days. That's pretty good I think.
Or still you don't believe me?