Ahsoka has a lot of Filoni in it. Lots of mystic star wars. Remember he's the one who introduced Nightsisters, World Between Worlds, etc. into the canon.
Stage is set as well for every "major" character to have an equal villain foil. Ahsoka has Baylan Skoll, Sabine, his apprentice, Ezra, the former inquisitor, and Hera, Lady Morgan, all before the ultimate hurdle of Thrawn's machinations.
Some of my favorite parts, Clancy Brown also returning to play his Rebel's Character. In my head forgot he played Ryder. Lothal in general. Lothal was a cool world design and it looked great with ILM's muscle creating it, the night sister's temple, wish more time was spent there, that set design was amazing, and of course Sabine's armor, always a highlight from Rebels, seeing it on the screen was awesome. Of course honorable mention goes to the modern star wars tradition of having big name stars voice droids with David Tennant with a strong turn as the Jedi droid who's name I should look up because it is just off enough I haven't remembered it yet.