When comparing Disa vs Threema, the Slant community recommends Threema for most people. In the question“What are the best messaging apps for Android?” Threema is ranked 6th while Disa is ranked 14th. The most important reason people chose Threema is:
Registration is handled by random generated IDs. No phone number needed.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Does what it's supposed to do, without bloatware
Pro Open source plugin API
Everyone can develop their own plug-ins.
Pro Easy to use
Disa is very easy to use and has an open source API, so many new services will be added soon.
Pro Customizable notifications
Ability to set different notification sound/vibration/led based on the plugin.
Pro Unified conversations
Ability to merge conversations from the same contact on different services.
Pro Friendly developers and generally good G+ community
Fast, decent replies to questions, even if they've been asked before.
Pro Many requested features
The developer team does actually listen to the community and adds requested features.
Pro Pushbullet support
Disa works great with Pushbullet, allowing you to answer from your PC.
Pro Many languages
Help and support in many languages.
Pro Disa takes privacy much more serious
Currently, the Disa team knows less about you than the website you're currently visiting.
Pro Great material design
With color-changing design with custom colors for each service.
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
Cons
Con Doesn't support most messaging apps
Con Disa doesn't follow the Google Design Guidelines
Hamburger Menu/Navigation Drawer (Side Menu):
https://www.google.com/design/spec/patterns/navigation-drawer.html#navigation-drawer-contentNo Animations:
Empty Pages/States:
Maybe a Launch screen?:
Con Does not support Google SMS
Con Closed source
Disa is closed source, so the development speed is capped of their team, no external developer can help or add features that are not on the route of the team.
Con Doesn't support WhatsApp at the moment
Con Attaching pictures suddenly failed; no working solution.
Con Smaller development team leading somewhat slow implementation of requested features
Though the main development (framework, etc) is moving along fine, things like quick reply and sending multiple images at once should've been in quicker.
Con Constantly asks to re-authenticate WhatsApp
Con Doesn't let you customize notifications per conversation or contact
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.