Casino are using different kinds of coins now so the players choose what ever they want to use coin. Dogecoin is one of the players use because the fees is very low and compared to the bitcoin and ethereum the range of fees is very high so dogecoin is most usable coin but I use XRP when I playing gambling when Im sending coin and withdrawing it because it is also cheap and fast transaction only minutes it arrives to your wallet not like bitcoin takes half hour or more before you spend your bitcoin which is not good but all the coins in that list is probably good coin.
Arent you afraid, that one day casinos will simply block withdrawals of Ripple, if Ripple continue to get claims and issues? Some exchanges delisted Ripple. Situation can be repeated.
Question to those who choose Dogecoin, Tron, Ripple, Litecoin - when you finish gambling, do you withdraw your funds or keep them on the site? If you dont more funds here and there often, then transaction speed is probably not so important for you. Maybe next time consider playing with Bitcoin?