Day One
Used by 10 peopleapps.apple.com ↗

“For anything with dated entries, like a work log, journal, or reading and watching diary, I'm a big fan of Day One, thanks to the date-oriented entries and sync across all my devices.”
André Arko Interview, Web developer · via Uses This 
“I also use Day One occasionally to (sort of) journal.”
Navneet Alang Interview, Freelance writer · via Uses This 
“Day One is amazing for all my personal writing, anything from journaling to jotting down poems and stories to morning pages.”
Madelin Woods Interview, Developer (Square), artist · via Uses This 
“I use Day One on my laptop and phone to remind myself to write in my journal.”
Chris Glass Interview, Designer (Wire & Twine) · via Uses This