I enjoy Evernote. It is an all-in depository of things I want to keep. I put reading materials, ideas, notes, documents I need to keep. But sometimes I just want to jot down simple notes and not necessarily make them archivable. It is like Notes in my iPhone. One limitation of Notes is that I do not know a way to sync the notes with other devices. I also like to centralize my notes so I pretty much use Evernote and clean up (i.e., delete) any unneeded notes after I used them. I looked into Simplenote, but again, it’s another service I need to connect to and have to remember. As much as I wanted to use it, I never got around to integrating it into my workflow.
Then I learned about Google Keep. It is pretty much the same as Simplenote but with one benefit: it integrates with Google. I use many Google services so Keep nicely integrates with my workflow. The app (iOS, Android) is fast. The website is minimalistic but functional, and it even integrates with Google Drive.
If you jot down lots of notes while you work, I suggest you look into Google Keep.