I'm almost certain that provably fair is a term used in online gambling and not with exchanges and trading platforms. 
Cobinhood is the only exchange with no trading fees, but not that recommended as there aren't many coins supported. I would suggest using Binance with BNB to get better fees.
Cobinhood is the only exchange with no trading fees, but not that recommended as there aren't many coins supported. I would suggest using Binance with BNB to get better fees.
Yeah, I got lost in words here, maybe what he meant is that a trading platform that is fair (no wash trading or fake volumes). I guess Binance is one good option to the OP.
Here is BTI latest report (https://www.bti.live/reports-april2019/). You can look at which trading platforms has fake volumes.