Silence, as it relies on PGP to secure your comms, and is otherwise ttransparent. The idea with PGP is that you don't care who can see your messages because they are end-to-end encrypted using public/private keypairs. Silence utilizes this in a very pure way. There are a couple considerations, I'll pro/con it to make it easier to compare Silence Pros * Pure end-to-end PGP encryption over SMS * You don't need to update it. If you and your friend have silence and have exchanged public keys, you will always be able to communicate securely with your friend. Cons * It uses SMS, which means you need a cell provider and they can see that you are sending encrypted messages between phone #1 and phone #2. But that is all they can see (no message content is exposed, as it is e2e encrypted via PGP) * It's SMS, video sending is laughably bad. Session Pros * More modern, can send 5MB videos and pictures via other devices. * Cross-platform: App exists on apple app store and google (though android will always accessible via f-droid or direct apk install) * No phone number associated. Cons * Due to the size and complexity of the backend network, it is hard to know if there are backdoors and/or the nodes you are routed through are spying on your comms * Needs to be updated regularly to stay in-sync with the backend network * Most people will install from the official app stores which almost guarantees it will be backdoored eventually. I have both myself. I use session when sending media, but fall back to Silence when I want to ensure a text message gets to the recipient, and gets there quickly.