I know some of what is said was tongue in cheek, but I do like the idea of something really simple. Like "your notes, your way", simple, short and to the point. But then again that's probably been used a million times already 
Fully agree that Joplin should shred it's "geek" image and last thing you want is a slogan that gives you the idea that it is only suitable for programmers and developers - while in truth even my 80+ year old non-techie dad is able to use it.
I wanna suggest one too:
Make notes, secured and easily.
Is this going to be the new UI for the website? If yes, looks really awesome.
Thanks, and yes it will be the new design.
The new design looks cool!
One suggestion would be to focus on encryption, markdown and open source in the description, maybe? I know this is anecdotal of course, but I believe them to be the key differentiator for Joplin and something on which I've managed to convince others as well.
EDIT: Ah, never mind. I thought this was work in progress, but just checked out the website. Looks fantastic! 
Thanks! Encryption and open source are mentioned below the tagline (as "secure" and "open source"). For Markdown, it's mentioned in a section below but I didn't put it below the tagline, because I'm not certain it's important enough to be there.
"We rule your notes!"
The new web site is up. No more taglines needed. 