I'll just add that the article detailing the vulnerability on desktop is here:

https://vxlabs.com/2017/06/10/extracting-the-jaxx-12-word-wallet-backup-phrase/

In short, the vulnerability exists if an attacker has access to your file system and is prepared to brute force your pin: this problem is far more significant on desktop because it's fairly easy to access application files/folders where as mobile operating systems use "sandboxing" to keep important files safer. What it boils down to is Jaxx will only encrypt your mnemonic phrase with a 4 digit pin (if that's even turned on), and this is a trivial layer of security at the end of the day.

Haven't used coinomi. I do still have Jaxx on mobile devices, never had a problem with it. I did have the desktop app but opted to encrypt the folder storing the important files, which I have to decrypt each time I launch the desktop app ergo I never use the desktop app :P