Both ETH and BTC have huge fees from time to time and I can't in good faith recommend them to anyone.
not all times . they are only expensive when their value is also high but thesedays tx fees are freakin cheap . thats why using btc or eth isnt really a headache .
I made the mistake of recommending BCH to merchants, but the hash war destroyed its stability, too.
bch didnt ever become stable because bch is still a crypto and all cryptos will always be volatile . but your recomendation is good , bch is more lighter and has a smaller fee compare to eth and btc .
I am also a merchant and would love to accept crypto payments but the volatility is one issue for me.
thats good if you will add the suport of crypto payments but you must adjust your pricing depending on the current value of the coins so that you wont loose .