Nowadays it shouldn't just about the coin, but about the provider as well. if a website can have few options like binance chain, ERC-20 i think it should be better
Binance smart chain got low fees and is fast but some might argue that it is centralized so it might not be the best option for some people, also adding any kind of ERC-20 token won't help as they are just tokens based on Ethereum blockchain and actually you have to pay way more fees to transfer ERC-20 tokens on Ethereum network than Eth itself, so it's cheaper to just use Ethereum.
Casino websites should accept some coins with privacy features and some other coins that are just fast for sending/receiving payments so that every customers is able to use a payment method that suits them the best, whether they choose based on their fees, privacy or speed should be up to them.
That would be a major problem if we were talking about such coin being a store of value for your wealth for the long term, but since we are talking about a coin to get fast and cheap transactions when you gamble then that is not a deal breaker, however by far the best coin when it comes to this is dogecoin, I know that many do not take the coin seriously because of its story and I get it but when it comes to fast transactions dogecoin is one of the best coins out there and should be adopted by more casinos so their clients have the option to choose it and gamble with it.