the success of your investment depends on how the marketing will succeed to attract more gamblers to play using the casino if there's nothing that the team offers it will delay the progress in terms of value, but if there are many available feature that investors will earn the chance that it will be supported by more investors and traders.
On the other-hand, if you have a decent amount of money to invest, adding more solid asset like BTC, ETH and BNB.
It's up to you though, your money is always valued by your decision with your investment.
You mentioned marketing there but speaking of it, all three of them are already doing it. I regularly see betfury, owlgames and the fairspin casino having their own signature campaign but if there is one that excels then I think that would be owlgames because they also have a bounty campaign which pays their participant with owl tokens (if I am not mistaken).
That must be worth it I believe because owlgames are being talked about lately more than their two competitors but I think they won't just let owlgames won the competition but maybe the two casinos are also cooking something and they will release it soon only to stay relevant on the game. Let see.