If forced, I'd say Dolibarr is probably the best for 'real' ERP use-cases. I say 'real' because ERP is a buzzword that has been beaten to death to describe things that don't even approach what it's intended to mean.
A close second is Vienna Advantage. IIRC the development actually came from former SAP devs who have real-world exposure to the problems ERP is supposed to solve.
We actually tested Axelor as well! At the time, their documentation was quite lacking (in English at least) to the point that their installation instructions didn't result in a working system. (We got it working using a windows system and an older version, but weren't able to do so on a Debian?? system with the latest version at the time) I would be very happy to hear that things have improved because Axelor is probably the most 'user-friendly' and 'pretty' system we tested - assuming it's functioning.
A close second is Vienna Advantage. IIRC the development actually came from former SAP devs who have real-world exposure to the problems ERP is supposed to solve.