Since AngilarJs is getting EOL-ed I'm trying to figure out how to migrate relatively large application without complete (and ideally significant rewrite) to something (what?) more modern.
We have ASP.NET 4.8 multi-page (not SPA) application with server-side DevExpress controls (grids mostly), regular HTML controls and AngularJs (50 simple controllers with few components/services) on top of that.
It is clear how to modernize ASP.NET 4.8 to Core.NET. DevExpress controls can be migrated to client-side counterparts. But I'm struggling what to choose for client side if I want to keep multi-page application. Migration to SPA is also possible but that will be a big rewrite.
So, this question seems opinion-based so may get closed, but I will try to answer.
From someone who's done this, there's no silver bullet I'm afraid. Even the chaps behind AngularJS realised this, that's why there's no direct upgrade path from AngularJS 1.5 to Angular 2+. There is most definitely going to be significant rework.
However, you should be able to keep most of your backend work. It seems like it's largely your frontend you want to upgrade. I would recommend going for Angular. It's close to what you were writing before, but is a lot easier to write in. You will most definitely need to retrain a bit though. There are significant differences.
In terms of SPA or not, I would actually recommend you take the time to move to an SPA but if you're against that, you can use hard links which will load up a new page each time.