According to me, Sports betting is most profitable. In some matches the odds might be small yet the chances of winning the bet are very high. Now what matters would be the amount of your stake, also there different markets to choose from and you can place parlay/accumulator market whereby with a small stake one can win huge amounts, yet the chances of winning the bet are small. Even though there are small , with research and analysis the chances of winning can be increased and minimize risk.
I would agree for sportsbetting is the most profitable among other gambling betting games/sites if you really know the type of sports you are betting on and also the odds are great if you actually hit those teams whos strong but out numbered of bets by some other people, and also sportsbetting will be a safe place for bettor to play on since you dont need to risk some bets to expirements such things to win like on dice sites.