Accommodations in Kyoto or Osaka?

I want to maximize my JRail Pass in the Kansai region as much as possible so I'm thinking of staying there for 7 days this upcoming May.

I am looking at the Kansai Region guide. Would I be able to see every prefecture in 7 days, potentially less? Not sure if I should stay in Kyoto or Osaka and be able to visit them all. Assuming it's a short ride from each prefecture on the bullet train. If so, which prefectures should I group together? Or do I need to do less than 7 prefectures since some may be similar and I can skip out on one?

I was also looking maybe to stop or even stay overnight at Nagoya on my way back to Tokyo. Is that worth doing? Or it's better to just visit real quick for a few hours then head back to Osaka/Kyoto?

They are 25 minutes apart by local/rapid train. They are so close.

Where you choose to stay should be based on what you wanna see in the area. Not maximizing your JR pass.

Osaka tends to be cheaper than Kyoto. But there is more to do in Kyoto.