I'm a big fan of Evernote and Microsoft's OneNote and am looking forward to the rumored Google note-taking app named Keep as well. But if I had only one note-taking and data capture app to rely on, I'd stick with only OneNote. Here are three ways that OneNote beats Evernote, and ways in which Google might beat OneNote with its rumored Keep note-taking app.
Better structure for large projects
I often take on large projects, notably books, that require a great deal of research, which I need to frequently refer to and reorganize. OneNote is ideal for these large projects, because it allows me to easily nest tiers of information, something that's not as simple to do in Evernote.
Integration with Outlook
I use Outlook for email, and appreciate OneNote's excellent two-way integration with it. If I want to send a page of notes to someone else, I can do it easily from inside OneNote. When I'm on a page, I click "E-mail Page" on the Home tab, and the page is pasted into the body of an Outlook email. I just need to fill in the people to whom I want to send the notes. There's more to Outlook integration as well, including syncing to-do lists between Outlook and OneNote. Evernote can't do this.
Integration with SkyDrive
Microsoft's SkyDrive cloud-based storage service lets you create OneNote notebooks, but more important is that it lets you share those notebooks with others. Create a NoteBook on SkyDrive, invite other people to share it with the Share feature on the File tab, and other people can not just see your notebook, but comment on it as well. You can also upload any of the OneNote notebooks from your computer to SkyDrive
Google's note-taking app
All this is not to say that Evernote isn't an excellent app as well. I use it quite frequently, although more for grabbing pages and information from the Web than for note-taking, for which I primarily use OneNote.
As for whatever note-taking app Google might launch, I'm looking forward to it. For information hunters and gatherers like me, you can't have too many note-taking options. I'd like to see it improve on OneNote by combining the best of EverNote with the best of OneNote -- Evernote's data capture and multi-device syncing capabilities with OneNote's superior structure for larger projects. As for integration with Outlook and SkyDrive, that's not going to happen, although equally useful would be integration with Gmail and Google Drive, which if it's launched, it will undoubtably have.