With ETH/ETC, as soon as ETC started trading it got dumped down to a very low level.
Then is quickly rebounded and went very high, I think up to 30% of the price of ETH, which was obviously assumed to be the strong side of the fork.
I wouldn't feel to confident selling straight away, you might also have to watch out for replay attacks, so be careful moving your Bitcoin/Bitcoincash around straight after a fork.
The ETC one is a forever unique case. To anyone from the outside looking in ETC was the far less offensive option. ETH had the personnel but basically shat all over itself though no one now seems to care.
Either eventual Bitcoin doesn't have that problem. I suppose it's entirely down to perception and where the economic majority will head. I don't think anyone other than the creators of Bitcoin Cash have any incentive to support it. It's dead intriguing all the same.
At this stage in the game the cash aspect is still the least important. People are looking for price appreciation, not spending money.