ERPNext (GPL V3, https://github.com/frappe/erpnext) is being deployed by many large companies as we speak. India's largest Stock Broker Zerodha (https://www.youtube.com/watch?v=4B6nfq1UR3Y) and biggest Listed Company (https://www.youtube.com/watch?v=jnoWwSBDQlI) are actively using ERPNext.
ERPNext is not open core like Odoo.
Disclaimer: I am the founder of ERPNext