It’s best to go for discount brokers like finvasia, fyers, 5paisa etc. Their main advantage is that you can cut out a lot of cost spending in the name of charges, brokerages etc.
For long term investment I am using finvasia because,
1. They give professional services with comprehensive trade reports that can help investors to track their fund movements over a long time.
2. With their trading platform shoonya, you can monitor your trades via multiple devices at any time, anywhere. This tool also has the best charting patterns that helps you to choose stocks that have long term scope.
3. They have zero charges for brokerages, clearing and account set up.
Also to add, they have good trading tools which can help you with stock selection for your long term investment plan as well. If you are looking for very long term investments like decades with very low risks and consistent returns, you can check out their mutual funds plans too.