Keybase has easy file storage/sharing, is cryptographically secure, AND gives 10 GB of free storage?
DING! DING! DING! We have a 
Keybase
Let's do a quick rundown, and I'll cover this in more details later.
- Private files are encrypted so that even keybase can't see the files you are storing with them!
- 10 GB of free storage!
- Mobile and desktop apps
- Integrates as a mounted drive on your computer
- Share files to the entire world
- Shares encrypted files with other users
- Links multiple personas across a large variety of internet platforms
- Basic website platform available
- And a whole host of more things
So, everyone uses online storage services like Dropbox and Google Drive.
Guess what. Those services have only basic levels of security. Your files on those services are only protected by basic protections while they are being sent to Dropbox, and while they're sitting on Dropbox, the hosting company has all the keys to view your files, so they can be hacked and viewed. Dropbox regularly scans all your files and gathers the info about you to better serve you files and sell to other companies.
Store your tax documents on there? Store your oh-so-sexy nudes and dick-pics on there? Store your health or insurance information on there?
I'm sure you'd prefer those things stay private.
If you're of the more paranoid bent, governments can give Dropbox a warrant and Dropbox will have to give your files to the government. Do a bit of gasp illegal downloading? Ding!
The long and short is that your files are not secure with these services beyond a barely-passable effort.
Online file storage is fantastic for lots of reasons, but one thing it is NOT is private. If you want to make sure your files are safe while you're uploading and downloading, and while they're sitting on the storage? Don't rely on these services.
Not only that, but they only give you 1 GB of storage. That's nice, but it gets filled up pretty quickly.
So, how to solve these problems?
Keybase 
Start with the fact that they encrypt all your private files BEFORE they transport the files across the internet.
Got a hacker sitting at Starbucks listening in on all your communications? Tough nuts! They can't see the private files you send to Keybase!
Then comes the really great security part: Keybase cannot decrypt your private files!
That's right. The keys to your files stay on your computer. Keybase can't open your private files even if someone is holding a gun (legal, metaphorical, or real) to their heads. Your files are completely safe. They only get decrypted once they are safely back on your computer.
And the cherry on top? This is all provided in a completely transparent method. Easy security? Yup, they have it set up so that you don't even notice that everything is encrypted.
Keybase is one of my favorite security discoveries of the last few months.
Go set up an account, enjoy your massive 10GB of free storage that is cryptographically locked up for fantastic privacy and is seamlessly integrated into your computer.