When dealing with cloud-based office productivity applications (documents and spreadsheets), the main contenders are obvious:
The Kit and the Kaboodle
Here I will deal only with Google and Amazon, rather than all major Cloud providers. I have not considered Apple's (iCloud is an ongoing disappointment) or Microsoft's (sorry, not going back, too many scars). The main issue that I experience with the Google and Amazon offerings is integration among kinds of files to back up, especially images, music, and standard office documents. The main disconnect (for Apple vs. Google) is the Music component. Both are now offering pretty much unlimited images, and a hefty amount of storage. For a small fee ($1.99 USD/month) Google provides 100gb of cloud storage space, plus unlimited images (compressed in some way, not native image size). While the location of Google Photos inside of Google Drive basically works, the edits on one side (filenames, for example) do not replicate to the other side.
Google Mail, Docs, Drive, Photos, Music
For Google, the integration of Mail (and Calendar) with Docs (cloud editors), Drive (all files), Photos (with sync to/from desktop and mobile), all work out well. The Music part is a separate app and sync, but as a basic backup and Web/App based access from other devices, it works great, and offers 50,000 songs of upload storage for free. That's a great backup plus access via any device through a browser or Google Play Music app.
I've been using free tiers of Google Apps/Drive for years and years, now grandfathered in. I don't mind paying some small amount per month, I don't need to pay nothing. Currently I pay the $1.99/month for the Google Drive 100gb storage, nothing for Apps, Photos, or Music.
Amazon WorkMail, WorkDocs, Drive, Photos, Music
Amazon has a bunch of similar features with their Amazon Drive and other accompanying products. Drive is unlimited Photos plus 5gb of files for Amazon Prime subscribers, and unlimited files of all types for $59.99/year. They also have a virtual desktop service Amazon Workspaces. For Amazon Music, there are two streaming options (Prime and Unlimited -- which starts at $3.99/mo). But the upload option is the one I am most interested in, and it is 250 songs for free (not including any bought from Amazon, which do not count against the limit), and $24.99/year for 250,000 songs.
For pricing, Amazon WorkDocs and WorkMail can be bought together in tiers that support both, for $6 USD/month.
Prices are currently $4/month for WorkMail and an additional $2/month for WorkDocs.
Yandex Mail, Yandex Disk
Another interesting competitor not mentioned earlier is Yandex Disk. The latest 2.0 version does not require files to be on a local drive. This solves a problem with most cloud storage, where a thin client can access through a browser, but anything similar to a native client experience synchronizes all files locally. One computer could initially upload a file system, and then later not need those files to remain local, as well as thin clients such as an intel compute stick with limited storage could have a full experience of file interaction.
Yandex offers 10gb of space for free, with additional storage purchased monthly at $1 USD/mo/10gb, $2 USD/mo/100gb, and $10 USD/mo/1tb. Yearly purchase offers a 17% discount and any number of each of the tiers can be purchased (example, 1.2tb would be $14 USD/mo or $140 USD/yr.
Yandex also has web-based editors for documents, spreadsheets, and presentations. Their sharing model is better than Amazon, as Amazon only allows for comment access, but with Yandex Disk, shared access can be granted.
Mix and Match for 2017
Besides having had generally good experiences regarding Google Drive, Google Apps, Google Mail, and Calendar, these are something I want to migrate off of Google. I simply don't trust them, and there is a lack of encryption involved. With Amazon, WorkMail (and WorkDocs) is available in the US and Ireland currently, so EU laws apply to the Irish servers. As well, the Amazon Simple Email Service (SES) makes it easy to manage transactional email and business use cases.
The free Google Play Music is still quite compelling, and I will likely stay on that, as I have close to 100gb (12,000+ songs) in music.
Yandex is a great solution for a personal user, there are useful security aspects to it. And while not as configurable at an enterprise-level, it is still a worthy offering. The sync and backup of Yandex Disk appears to be more robust and functional than that of Google Drive.
Redundancy for email is difficult to achieve based on the nature of a single email address being mapped to a single mailbox. This still needs to be worked out. However for file backup, filesharing, and editing, using both Amazon and Yandex is a viable solution that is fairly inexpensive (<$10/mo).
Note: there is also Proton Mail, which is an even more secure (than Yandex) email-only service.