I haven't used Google Drive for years. The ones I'm using:
mega.io: The best for private, sensitive documents. E2ee ,
open-source. 15GB space free for a lifetime and
the rest is free for a limited time. The desktop sync app is easy to use, and I like it a lot. If you are using the other cloud storage providers, like Google Drive, the staff at Google can view your documents aside from yourself. But with Mega, only YOU can view your files. All the files are encrypted locally in your PC by the Mega Sync app before uploading them into their server online.
More info about this here and you can sign up at
mega.io website.
Nextcloud storage: There's plenty of cloud storage providers to choose from. Just go to
https://nextcloud.com/signup/ , wait for the page to load and then click on the "change provider" link (press Ctrl + F if you cannot find this link) to select more providers. If you want the biggest free cloud storage, go for
Tab Digital (8GB free). I prefer any cloud provider from Switzerland due to their strict privacy laws.
Yandex Disk: Not private, but if I want to upload private documents, I would encrypt with
Cryptomator first and then sync.