When comparing Disa vs Brosix, the Slant community recommends Disa for most people. In the question“What are the best unified messenger apps for Android?” Disa is ranked 1st while Brosix is ranked 9th.
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 Excellent solution for companies who would like to encrypt their office communication
Brosix uses strong 256-bit encryption that secures ALL communication channels.
Pro Brosix is available on all platforms
This includes Android, iOS, Linux, Windows, Mac.
Pro Easy to use
Brosix IM facilitates the internal communication and increases office productivity.
Pro Affordable
For $1.70 per user per month voice & video chat, screen-sharing sessions, send unlimited files regardless of the size, etc.
Pro Great admin tools
The Enterprise version of Brosix allows the Administrator to manage their own and unique network. The Admin has also full-control over the archives of all chats within the network.
Pro Easy to use
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 enough Admin controls
Con Poor mobile version
The mobile version of the application contains only a few of the features that the Desktop client has.
