As far as I concerned, any broker providing tight spreads with competitive commissions, high leverage with excellent execution statistics, and an ECN execution model with a volume-based rebate program will rank among the best for scalping. You have to choose from such ones. There are lots of such brokers in the internet and you can read reviews and draw conclusions. In my opinion, everything might be revealed only due to your personal experience of trading with particular brokers. The more options you will test, the more you will start to understand what exactly do you need from a broker in order to run successful trading activity.