When comparing Signal vs Line, the Slant community recommends Signal for most people. In the question“What are the best messaging apps for Android?” Signal is ranked 1st while Line is ranked 29th. The most important reason people chose Signal is:
Signal uses an advanced end to end encryption protocol that provides privacy for every message every time.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Provides security and privacy
Signal uses an advanced end to end encryption protocol that provides privacy for every message every time.
Pro Free and open source
Signal is free and open source software, enabling anyone to verify its security by auditing the code. It's the only private messenger that uses open source, peer-reviewed cryptographic protocols to keep your messages safe.
Pro Supports encrypted group chats
Pro Has a desktop app
Signal Desktop can be used on multiple devices and has most features of the Android version, although it still requires you to register with your phone.
Pro Supports sharing of various different media types
Signal supports: emoji, pictures, videos, audio, contacts, any location and GIF.
Pro Note to Self feature
Allows you to "send: messages to yourself and sync to desktop so you can use Signal as a kind of encrypted Pushbullet alternative
Pro You can easily view all media exchanged
You can easily view all media shared in the chat without scrolling back to when it was shared.
Pro Annonymous Sender (Encrypted)
The sender credentials can be encrypted with the rest of the message, leaving only the recipient address readable by the Signal server. Even if Signal wanted they couldn't see who is talking with who by this mean.
Pro Works everywhere in every country
Unlike most messenger apps, Signal works reliably in all countries by securely circumventing internet censorship.
Pro Recommended by Edward Snowden
Edward Snowden uses this messenger and recommends it to everyone who is concerned about his privacy.
Pro Large celebrity and public figure usage rate
The caveat is that they are in Japan, but the app is commonly used to 'follow' public figures.
Pro Enormous, constantly updated stamp collection
Since many brands use stamps for promotional purposes, everything from movies to food brands to Taylor Swift have released stamp collections.
Pro Photo filter and editing capabilities
Users have in-app editing tools, as well as Line's separate camera application, which has additional tools.
Pro Integrated social network
Similar to Facebook's timeline.
Cons
Con Needs access to your phone number and contacts to work
Con Single device
Signal can only be registered to one mobile device at a time. But you can link Signal to Signal Desktop.
Con Servers hosted in the US
A security risk due to National Security letters, which require giving up data to the US state, and making it illegal to disclose that.
Con Unreliable notifications
Sometimes messages won't be received if the Signal app has been closed for a long time or hasn't been opened after booting the device.
Con Account is locked to the Phone Number & Device
The entire account is locked to the phone number, which cannot be changed. If the application is installed on a new device with the same phone number, the previous account data will be wiped.
Con Users have been concentrated in Japan
Of the 360+ million registered users, the top country is Japan (50 million). Thailand and Indonesia are 2nd and 3rd with 33 and 30 million, respectively, with very small market penetration in the US (10 million, 11th place).