A) Mint for most financials. iCloud for storage of documents.
B) Apple Health for keeping track of my records. For ad-hoc stuff I use iCloud to store the documents.
C) Product and service info I use iCloud for. Logins and credentials to them are stored in my family's 1Password vault.
D) All legal documents stored on iCloud.
E) For photos and videos I use iCloud Shared Albums. It's unlimited free online storage of photos. Otherwise it's a mix of iCloud storage and the Notes app on Apple devices.
Obviously you can tell I'm deep in the iCloud ecosystem but personally I feel it's worth it. The synchronization and ease of use for my family is well worth it. For what it's worth I'm on the 200GB plan.