Which OS would you recommend to run Electrum multisig wallet on? How does it compare in terms of security to running Windows 10?
I'm no expert, but Linux is definitely have better secure system & you actually have some privacy. There are various linux distro & there's no things such as best linux distro, but my recommendation are :
1. Ubuntu, Linux Mint or Manjaro Linux if you're beginner
2. Qubes, ParrotSec or Gentoo (with hardened user/profile) if you have serious privacy or/and security concern. All of them are categorized as niche or difficult OS, so don't expect much help or guide if you're facing problem related with your OS.