These tools are all fantastic! They do a lot of the same things in slightly different ways, so you’ll need to find out what works best for your style of organization.
Evernote can be life changing. Scrivener is an amazing tool for drafting large written works and research projects. DayOne is a terrific digital journaling tool. iAWriter is excellent for distraction free writing. Many of these can double as checklists and some are cloud based so that you can access your work from any device.