I use many apps every day. My favorite one is fax app right now. It's a perfect tool to send fax via phone. It has built-in scanner and e-signature. I just need to choose phone number. Useful app for everyone today. Now it's one of my favorite apps.
Photoshop, lightroom and Luminar, the last one is my favorite. It is an alternative for photoshop for MacOS. I found tutorials for beginners here https://skylum.com/blog/how-to-create-black-background-on-your-photos . Luminar has all fundamental features like layers, masks, blending modes, transformation tools, editing brushes, and clone and stamp tools, plus advanced AI-powered tools. As for me it's a must have app for every photographer today.