Best soil to buy or mixture to make?

I’m a plant parent of 12. All are thriving minus my Monstera Deliciosa. After some research, I decided to repot my Monstera and do some other things to try and save her.

I also need to repot some other plants that are growing pretty fast.

In deciding that, I figured maybe I should buy better soil or make a mixture myself.

Any advice on what to get? All of my plants are tropical.