We all have bad days...
So the question is...if you loose many times in a row, what would you like at most - a cashback from what you've just lost or a bonus to go on?
Technically speaking, Cashback is a bonus too that based on what you earned points in exchange for money. I don't know what kind of bonuses you are pertaining but rakeback is the best for me since its the percentage of the total profit the casino that being distributed to all players. Relying on cashback percentag of your loses is nonsense since you need to lose in able to claim while other bonus can be claimed regardless if you win or lose.