When comparing Threema vs Antox, the Slant community recommends Threema for most people. In the question“What are the best messaging apps for Android?” Threema is ranked 6th while Antox is ranked 28th. The most important reason people chose Threema is:
Registration is handled by random generated IDs. No phone number needed.
Specs
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Pros
Pro Registration without phone number
Registration is handled by random generated IDs. No phone number needed.
Pro Encrypted communication
Provides complete end-to-end encryption.
Pro Company behind Threema is based in Switzerland
Pro Servers in Switzerland
Privacy laws protect the data Threema has.
Pro Supports encrypted group chats
Pro Provides a web client
You can control and message with friends via Threema Web, the official web client for Threema.
Pro Ability to send pics and videos
Threema supports sending media messages such as video, pics and even voice messages.
Pro Group chat polls
Pro Allows verification of contacts identity via QR Code

Pro Free, open source
Antox is licensed under Creative Commons with source code available on GitHub. Being open source makes it possible to make sure your messaging are not controlled by a corporation.

Pro Peer-to-peer
There is no middleman, all communication happens between the users.
Cons
Con Not free
Unlike many other options Threema is not free as it costs $1.99 for the app.
Con Single device only
You cannot use multiple devices to send messages. However, it does have message mirroring on a web client.
Con No cloud sync
E2E encryption means no cloud syncing of messages.
Con High data usage
Antox uses the Tox protocol which is Peer to Peer, so there will be high data usage and battery drain. WiFi only mode is currently recommended for now.
Con Still in early development
Antox is still really early in development, being in beta currently.
Con Battery drain
Antox uses the Tox protocol which is Peer to Peer, so there will be high data usage and battery drain.
