I use calm but I'm not too happy with it. It has a few basic features that I use but because 85% of their content is only part of a monthly subscription, I can't judge all of their meditation features.
I don't use the apps specific for meditation. Early in my practice I was taught that any moment you experience awe (beautiful sunset, cute animals, glorious painting), are fully in the moment (swimming, jogging, biking, painting), or focus your thoughts (contemplation, breath, sound, music, image) that is meditation. The apps only complicate it for me.