Whiteout.io is a chrome app for email, plus an android app with key-synch between the two. It's still early stages, so it has some issues (like indexing all your emails, since forever, and overheating your computer). But it's very promising.

Most people want to continue using webmail though. That's why Mailvelope is so awesome. Continue using webmail, but just have an extra button added which opens up an editor with a bit "encrypt" button. Pretty easy, and pretty safe.

There's also protonmail.ch tutanota.de and several others in early stages.

Mutt and Thunderbird come to mind.

Clawsmail as well :)

GPG in Mutt is fantastically well integrated.

Now, of course, you have to get used to Mutt first :)

Thunderbird with Enigmial also works quite well. I use it everyday.