This one’s up for debate. Online slot machine games are incredibly popular among these casino players looking to hit it large, particularly because of the progressive jackpot aspect. On the felt, it is a tossup in between online roulette and blackjack. Online roulette provides close to 50/50 odds if you bet on evens or odds, colors, 1-18, or 19-36. And online blackjack is well-liked among those who love to count cards and attempt their hand at busting the house.