We made this feature by feature comparison with SAP BO (not R/3): https://www.odoo.com/page/compare-odoo-vs-sap

And all our comparisons whitepapers are here: https://www.odoo.com/fr_FR/page/odoo-white-paper

For all it's bloat and crappiness one thing that SAP provides is end to end process management. Want to process the bill with your banking provider and have that included in your tax returns automatically and plan the freeing of a bed with the emergency control room? Well SAP will do that (at a price and with consultancy). That's why SAP is what it is.

It works, but at a cost