When comparing Mirage vs Disa, the Slant community recommends Disa for most people. In the question“What are the best messaging apps for Android?” Disa is ranked 14th while Mirage is ranked 39th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Includes filters
It's possible to change the look of images and videos via filters.
Pro Groups
It's possible to send messages to multiple people at once. Either by setting up a group or by selecting a bunch of people individually. Groups can also be muted if they get too noisy.
Pro Messages self-destruct after they've been viewed
Once a message has been viewed, it gets deleted from Snapchat's servers. Thus, unless a person chooses to save the message manually (a notification will be sent if a user decides to take a screenshot), there will be no trace of it left. It enables a bit more consequence-free, in-the-moment kind of communication to occur.
Pro Generates a contact list
Once the account setup process is complete, Mirage generates a list of people from your contacts that you are most likely interested in sending messages via Mirage.
Pro Interface designed for getting things done quickly
Tap a contact to take a picture, tap and hold a contact to record video. Tapping the screen will allow you to add text to photos and videos just taken. Swiping the screen changes what camera is used. Swiping from the side allows sending text and voice messages. Voice messages are recorded the same way videos are by tapping and holding on a contact just from a different view.

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.
Cons
Con Buggy
Messages get lost users have trouble getting their codes to log in and has trouble actually finding the users contacts.
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
