I struggle between the following...

1. Shaak Ti's death by Grievous

2. The Seeds of Rebellion OR Confronting the Chancellor, whichever.

3. Yoda's Exile to Dagobah

Despite the potential futility of it, I think it I pick Yoda on Dagobah, as I think it is worthwhile to see his exile just as we see Obi-Wan's...and yes, I'm aware of the purpose was being to focus on the Skywalker family, but still, I stand by my vote.

Cool to see yoda go into exile wish we saw that. However Shaak ti doesn’t make any sense at all and doesn’t work