ETRADE is the best one in my opinion from personal experience. They are very penny friendly. TD AMERITRADE is the worst broker. They are always not allowing many to buy so many different Pennies. MYEC $$
ETrade! omg im actually glad TD Ameritrade is stupid and doesn't allow trading on OTC's because I switched to ETrade and my god ETrade overall is 10x's better IMO, Scottrade is also another good choice :)