Bitcoin as the main currency and doge as the alternative currency. Doge is the best coin for gambling because the fee is low and the confirmation speed is fast.
I am unable to understand that why people are wasting their bitcoins in gambling because gambling is riskier than other aspects in which one can easily invest these bitcoins and can get huge profits from it. I think if you have a huge craze of gambling, then you should better go to real casinos and spend your real life currency to gamble.