I love using Penzu. I use the free version, though the Pro is just $19.99/year, I found I didn't need the options it offered. It is so helpful for me because I can write in my personal journal online and access the same journals through the Penzu (free) app on my phone as well. That let's me write in one place wherever I am. That has been hugely helpful since it all synchs together so I'm always up to date wherever I access the program. I also like using the "talk to text" function on my phone to dictate my thoughts into a Penzu entry as I will usually have several documents or entries working at the same time.

Additionally, I have been enjoying Rocketbook.

It's a small journal where you can write with their special pen and each page has a QR Code. So if you are a more "pen to paper" writer, you can write on the page (printing only) and scan the page with the QR Reader on your phone. The program turns your writing into text in a document (Word or comparable) and you can continue to work on what you've written.

Happy writing!