Accounting dashboard architecture [closed]

I've been tasked with updating an old dashboard showing graphs and different types of analytics, pulling data from an accounting software's mssql database.

My task is to add support for another accounting software as well. The code is old and very ugly, so I want to pretty much refractor the whole project, but I'm a bit unsure what design pattern would be best.

My thoughts so far has been views showing the same graphs, tables etc. Controllers presenting views, and repositories for the different accounting software databases. The data from the different repositories would obv be different, somewhere I'll need to standardize it before sending it to the controller (?).

Or how would you do it?

I'm used to MVC, but recently I've found it a bit shortcoming on larger projects. Which other architectural patterns would you recommend me to learn more about to improve myself?