Who is more powerful Radha Rani or Mata Sita?

It is wrong to make this comparison in the true sense, but if it is said that Radha Rani had the power like Mata Sita or not, then it can be said that she had exactly the same power as Mata Sita. Because both are incarnations of Goddess Lakshmi 

Let's see some stories of Radha Rani

Story of birth of radha rani

 

* The most popular story of Radha ji's birth is that Vrishabhanu ji found a divine girl lying in a golden lotus in a beautiful cool lake. They brought her home but the girl was not ready to open her eyes. Father and mother understood that she could not see, but Prabhu Leela was such that Radha wanted to see Shri Krishna first. So, when he encountered Shri Krishna ji in child form, he opened his eyes.

 

* King Suchandra, the son of Nriga and Kalavati, the Mansi Kanya of the ancestors, meditated for a couple of years and sought the blessing of Radha to receive Radha as a daughter. Consequently, he was born in Dwapara as King Vrishanu and Queen Kirtida. Both became husband and wife.

Gradually, the time of the descent of Shriradha came. The news of Kirtida's pregnancy began to spread as a source of happiness in the entire Vraj, all eagerly waiting. He came to Muhurat. Shukla Ashtami Chandrawasar of Bhadrapada sky became cloudy during the mid-day. Suddenly a light spread in the maternity house, it was so intense that everyone's eyes were closed.

A moment later, the gopis saw that a little girl, lying with the radiance of Sharat Chandras, was lying in front of Kirtida Maiya. There are heaps of divine flowers around it. With its incarnation, the stream of rivers became clear, the directions became happy, the cool wind began to flow from Arvind extending the Saurabh.