I've found NitrogenSports to be the best option for sports betting at the moment and haven't had any issues using them.
Sure Nitrogen sports is one of the best sports book out their and they have one of the best odds and they do provide many offers for playing in the site and to me it is a good alternative to directbet but you have to register an account before playing in them but they do provide swift withdrawals .
there's actually a lot of good sportsbetting, i like nitrogensport and anonibet, but I think one of the reasons why many sites are still less popular than directbet the first is less promotion, although they have better systems and odds that are bigger than directbet would be useless if they do not have good promotions like directbets, and second, gamblers prefer to be flexible and anonymous so they do not like creating an account first for gambling,
I do say that this gambling option is not good to earn the bitcoin. Most of the whales and millionaire playing the betting and other gambling games for fun only. If you take these as serious you will be consider as fool. Most of the gambling site use to promote the site using signature campaign and social networks.