xournal - Lightweight notetaking and sketching app.
GoodNotes - GoodNotes lets you take notes and annotate PDF documents.
Epsilon Notes - Common Mark editor for Android and Windows
Stylus Labs Write - Write is a word processor for handwriting, designed primarily for tablets with an active stylus.
Notebooks by DroidVeda LLP - Notebooks is an app by DroidVeda LLP that comes up with features to help you in creating customizable digital notebooks so you can take notes as well as can also attach drawings to notes.
OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.