* Planets don't have stars. Planets orbit stars.
* Stars exist in galaxies. Galaxies are vast collections of stars, gas, dust, and other celestial objects.
So, the question you might be asking is: Which galaxy has the most stars?
We don't know for sure which galaxy has the most stars. Astronomers continue to discover new galaxies and refine their estimates. However, the current leading contender is IC 1101, a giant elliptical galaxy estimated to contain trillions of stars.
Let me know if you'd like to learn more about galaxies or stars!