I am a retail trader, trading for the past 30 years. I came accross different brokers. It is hard to say who is the best broker.
Thanks to the internet revolution, now a days, it is the computers talk on behalf of brokers. Trading is made easy, all you have to do is think about the your investments. Transaction will take in seconds.
I tried Sharekhan, Reliance, ICICI, Indiabulls, RK global and Zerodha. I have varied experience with different brokers. In this 30years of trading, I never came accross a single broker who do good to the retail investor.