Raiblocks is another coin that have no confirmation time and zero fee and I think it will be accepted in some casino soon because nobody wants to wait for hours to get confirmation and pay high fees just to move coins in and out of the casino.
What other coins you guys think can be viable option for crypto based casinos?
I agree with you that Dogecoin is probably the best coin for gambling. Though not just because its transactions are cheap and hassle free, but also because the minimum allowed bets in dogecoins are cents only in most casinos. Indeed, it also depends on a casino and their specific rules, but it is almost always the case that minimum bets in Dogecoin are lower in dollar equivalent than in any other coin.
So my point is that any cheaper coin would be better for gambling than a more expensive one, provided all other things are equal, of course.