VI ?
VII Deception arc and Maul/Mandalore arc.
VIII Younglings arc, Ahsoka/Chewie arc and Temple arc
IX Order 66 and Yoda arcHi, Smudger !
Like MalàStrana said, the Tarkin arc would be great. I’d love to see the Mortis Arc which fits with the continuity of SW Rebels. Not sure if those 2 arcs could be tied together.Can’t wait for episode V.
Tarkin and mortis are in my thoughts for VI.