I recommend Canvas-LMS by Instructure
Open Sourced Code with paid SaaS option: https://github.com/instructure/canvas-lms/wiki
As of June 15th: "adopted by 189 institutions (including names like Brown University, Auburn University and Wharton School of Business) and about 2.7 million users" from http://techcrunch.com/2012/06/15/cisco-teams-up-with-instructure-to-move-the-worlds-largest-it-classroom-to-the-cloud/
I managed a Moodle project and we continually wrestled with any coding changes and overall found some of the UX counter intuitive.
