First of all, Slots are also among in your " Crypto Games " category but I prefer to call them Casino Games because there is also a specific game for the Crypto Games category. Games like Axie Infinity, Sandbox, My De-Fi Pets, and the likes. Now on your question, the answer would be the casino games. To be more specific ; they can be Crash and Mines. Their multipliers are over millions. Slots can only come in second. I think the highest max multiplier slot game that I heard is Tombstone Rip and it was from the provider called No Limit City.
How can slots be categorized as crypto game because in my opinion this game is game that has been popular for long time before crypto-based casinos developed and there are many slots in fiat casinos so saying it is crypto game category is not the right thing.
A crypto casino is gambling place that uses crypto currency and all the games in it that have been provided by the provider only follow the workings of casinos that use crypto currency as means of payment for bets.
Returning to topic, if we study all the games that have been provided by the casino actually big chance of winning will only be had when the gambler is lucky so it can be interpreted that there is no single game that can guarantee bigger chance.
Maybe skill-based games will be able to provide greater opportunities to gamblers but that depends on how the gambler has the knowledge and dexterity in playing the game.
On one hand, I know slots bring in large X's, but it is quite rare and you have to be really lucky. On the other hand, I saw people get massive multipliers on crypto games like Crash after a couple of minutes of playing. So which is it?
Maybe you focus more on Crash games, and that is why you often seen those huge multipliers in them than on slots.
Actually all games that give multipliers are the same only you will win and get big multiplier that breaks when the gambler has luck but it seems like we all here have different interpretations of opinion.
Remember that luck will bring gambler closer to winning than just believing in game that may easily issue multiplier but it is not certain that the multiplier will be achieved and you will have it.