There is no one online sportsbook that is the best, but there will be an online sportsbook that best fits your betting needs.
You need to think about what type of bettor you are and take a look at what sportsbooks specialize in the type of bets you will place.
You should also check out what online sportsbooks are operational in your state.
According to BettingScanner's ranking system, Pointsbet has ranked the best sportsbook of the year. The online sportsbook is now active in several states, including New Jersey, Pennsylvania, Colorado, Illinois and more.