I strongly suggest taking a look at Evernote which is primarily aimed at the academic world, it features depending on the selected plan:
Note taking with stylus support & audio notes
PDF storage, organisation & searching
Sharing within groups, etc.
Cross Platform Support including Mobile
I have recently started using Typora and Dropbox for note taking. Typora is a Markdown editor, but has very good WYSIWYG capability. You get both the speed of writing in Markdown and the ease of looking at nicely presented formatting. Of course, you can switch to source code mode if you want. With Dropbox, you get local copies of your files available offline,...