Betfair has one of the biggest and most flexible sign-up bonuses. You get to pick if you would like a $50, $250, $500, $1000 or $2500 bonus. Unlike some other sites located on the Ongame network, Betfair pays out the bonus in rates. This means that no matter which bonus you pick you dont have to clear the whole amount! This is great as not all of us are born as grinders.