@saranrajk The simple answer is with AAS allows you to scale to any size without processing or size limitations. Without it, you'll be bound by the size of the PBIX publish limitations.
The other is that it is still the only place to centralize your models, but that is going away at some point based on the public roadmap that outlines shared/certified datasets (dataset available across all workspaces) - https://docs.microsoft.com/en-us/business-applications-release-notes/April19/business-intelligence/p...
Overall its a tough question as MSFT continues to build out more enterprise features into the tool. You just need to walk through the specific scenario's of how you are using things, it could also be a better option to increase to a PBI premium license vs. AAS...
Another area is data sources, does AAS connect natively to any Azure sources that Power BI does not yet.
I've been mulling this over as well, and its likely that I'll go Premium first, then roll into AAS if I absolutely need to. But I don't forsee extremely large models in the vast majority of my future use cases, so the agility of small shared datasets fits my model.
