Give each Kyoto area enough time
Arashiyama and Higashiyama are both strong, but they serve different days.
Choose Higashiyama
Choose Higashiyama for classic Kyoto atmosphere, temples, old streets and walkability.
Choose Arashiyama
Choose Arashiyama for nature, river scenery, movement and a clearer excursion day.
Let the number of days decide
With only two Kyoto days, Higashiyama is usually the safer first-trip choice. With more days, Arashiyama becomes easier to justify.
Practical rule
Do not rush both into one day unless you accept a harder pace.