Which is the most powerful rocket in the world?

NASA’s SLS rocket will be the most powerful rocket in the world when it is launched in 2021. However, it could be overtaken by Starship of SpaceX as the most powerful rocket in the world, if the trials are successful. You can read about the GSLV Mk III – A Comprehensive Overview of Heavy Lift Launch Vehicle in the given link.

Further readings:

1. Mars Orbiter Mission (MOM) – Payloads, Launch Vehicle, Achievements
2. Reusable Launch Vehicle – Technology Demonstrator (RLV – TD)