calculation of free energy

Hello everyone, I hope you’re all doing well. I have a question about free energy. Would someone be kind enough to share their knowledge and help me?
I want to calculate free energy for my molecule. but I am baffled. I don’t know which technique is more accurate.
-Free sampling
-umbrella sampling
-Thermodynamic integration
-clog p
-py MBAR
or Methan in water(Gromacs tutorial)
are these methods related to my molecule structure?
Thank you in advance.