When comparing Antox vs GroupMe, the Slant community recommends GroupMe for most people. In the question“What are the best messaging apps for Android?” GroupMe is ranked 23rd while Antox is ranked 28th. The most important reason people chose GroupMe is:
GroupMe has a built in function to read receipts.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

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.

Pro Reads receipts
GroupMe has a built in function to read receipts.

Pro Great web client
GroupMe has an excellent web client that can be used to send and receive messages and manage groups from the desktop.

Pro IFTTT Integration
Allows sending messages from web services via IFTTT.

Pro Integrated calendar
It's possible to add location and time with reminders directly in the GroupMe app.

Pro Makes it easy to silence 1 or all groups
GroupMe has settings that allow muting a single group or turn off all GroupMe notifications from within the app.

Pro Does not require everyone in the group to have a smartphone
GroupMe can set up a custom phone number which allows people without the App to send and receive messages. This makes it easy to add anyone to messaging.
Cons
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.
Con Drains battery fast
GroupMe, in order to have a constant connection which allows for notifications drains the battery of a device quickly, which is not ideal for a messaging app that one needs on time notifications from.
