256GB. 64GB is a cruel joke.
The second you get on to Apple Arcade and download a couple of apps (along with a decent selection of essential multifaceted apps we all tend to have installed) and 64GB will fill up quickly. You'll likely always get back the extra spent on the higher storage long into resale value if you sell it on as even used buyers of older models pay a big enough premium for the higher storage models.
I'm sure there's a lot of stories about why, but let me narrow it down to two...
1. you pick up your iPad to use an app and it's been offloaded.... you're either out and have a slow public WiFi network or can't wait for it to download... you might lose interest and pick up your phone or do something else.
2. "Please delete 4.8GB of data to install iPad OS 17.0"... app-by-app, you go removing things you need and wanted. You update it and never remember to reinstall them. The horrors
Avoid both by opting for the 256GB is my vote