There are so many things that I loved about new modelling experience but here are my top two picks which I loved the most.
1. Ability to open Lists, Line Item Subsets, Modules and Dashboards in their own tabs. This removes the need to go back and forth between Modules->Lists->Line item subsets.

2. Line item Subsets(LIS), being carved out of General Lists Section & getting their own well deserved place.
What's your favorite?