I'd recommend a Samsung Galaxy Note tablet with LectureNotes from the Google Play Store.

I use a Note 10.1 2014 edition now, but will likely upgrade to the Note Pro 12.2 soon. Depending on your preference, you can get a Note Phablet at 5.7 inches (too small imo), or Note tablets in 8.0, 10.1 or 12.2 inches, depending on your preferences. LectureNotes is an excellent app with a very active developer.

I've also see recommendations for a Windows 8 tablet with pen input and OneNote, but that's not for me, even if the new Microsoft Surface Pro 2 looks vaguely interesting.