Google drive has some terrible integrations to 3rd party apps, making it extremely messy to manage alot of folders at times (folder endpoints are in the root folder, but dropbox uses /apps folder to make things clean). You don't see 3rd party integrations to google drive as often as dropbox because its API is subpar.
Google drive also can get someone confusing with how it integrates with things like google spreadsheets when you want to keep non-google things seperated
Dropbox has the fastest sync rates by far, and the largest number of integrations. You also have useful features like selective sync as well
Icloud has some subpar sync rates from when I use it. Personally, I do IT for family members who own apple products and I can definitely tell you I have spent at least 3 hours on tech support with a apple lvl3 tech just to resolve some basic issues. Dropbox never had that problem.
Amazon, I have not tried it. Dropbox used to use a lot of AmazonS3 until it migrated to its own storage solutions last year? so you can't necessarily go wrong with them. However again, 3rd party integrations is not there
Mega while its doesn't offer a lot of 3rd party integrations, and I can't attest to any of its quality
I used to be in the same boat as you comparing prices to GB of storage, but this is a highly inaccurate way of benchmarking cloud solutions.
Your benchmark needs to consist of
- Cost vs. Storage Size
- Folder complexity VS. sync/index times
- File size VS sync/index times
- Number of 3rd party integration
- Privacy concerns
- Other features (selective syncing, revision control for 1 year, etc)
At the end of the day I use dropbox since $99/year is not a whole lot anyways. I'd rather pay more for a better solution.
I have a few personal files encrypted using boxcryptor that I run alongside with dropbox