IMHO the most important and enduring language will be the one embedded natively inside your database of choice. SQL and it's many add-ons and extensions are the core foundation of an ERP system (which over it's lifetime will probably be interfacing with different external clients written in several other front-end languages). Model your business rules tight in the tables with triggers and stored procedures handling the standards like cascading updates and deletes, and all the non-standard data transformations handled by your database code, enforcing the business rules of your Enterprise at the core. SQLServer, PostGre, MySQL, SQLite all are good options

Did you know about TwinBasic? Maybe try this as an escape hatch from VB6. TwinBasic is free but runs slower than normal until you buy a monthly subscription to get full version and your code will run about 3x faster than the free version of TwinBasic. My broad recommendation is the following - convert the DBase to a modern database like SQLite or SQLServer, hopefully with the VB6 intact and still running the same, so now you have the data layer more solid - convert the front-end VB6 to TwinBasic. With a bit of luck your code will compile with little to no modification. - you might be able to stop here, with a modern TwinBasic application running your VB6 after conversion - otherwise, my next step would be rewrite your VB6/TwinBasic forms as React frontend with .NET server code running the backend (maybe this code is installed on your local machine, maybe a remote server, maybe both). - This is now mostly a rewrite of the frontend with React (initially inside embedded TwinBasic web browser control) As the new UI, and incrementally converting the backend to .NET until the app is able to run completely browser-based, then you can leave the TwinBasic code once you no longer need to support desktop installations. Learn more about TwinBasic here: twinBASIC GitHub twinBASIC Updates