When comparing Allegro vs Defold, the Slant community recommends Allegro for most people. In the question“What are the best 2D game engines?” Allegro is ranked 12th while Defold is ranked 21st. The most important reason people chose Allegro is:
The Allegro community has produced a lot of great tutorials and resources. Allegro [Wiki](https://wiki.allegro.cc/index.php?title=Main_Page), Mike Geig's Allegro [Tutorials](http://fixbyproximity.com/2d-game-development-course/), Rachel Morris' [Tutorials](https://www.youtube.com/watch?v=E4RqHtEAAds), CodingMadeEasy's [Tutorials](https://www.youtube.com/playlist?list=PL6B459AAE1642C8B4&feature=plcp).
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Supports desktop and mobile
Support for Windows, Mac OS X, Linux, iPhone, and Android

Pro Good engine architecture
Allegro is well designed, easy to use and has many useful features.
Pro Good documentation and lots of tutorials
Since it has been in development since mid-90s with hundreds of people contributing to both the engine and documentation, it has all of its bases covered when it comes to standard support.

Pro Per-platform library optimization
Allegro uses DirectX for Windows, and OpenGL for other targets.
Pro Freedom to implement your own game engine
You are not bound to the limits of existing game engines, and you can actually implement your own engine.
Pro Easy to learn
Defold uses Lua, which is regarded as an easy to learn language by most.
Pro Completely free of charge
Software and online dashboard are free of charge.
Pro Good combination of visual editing + code (Lua)
You can do a lot with drag and drop, but you're not limited -- the code (Lua, which is easy to learn) allows you more power than just visual editing usually gives you.
Pro Fast results
Going from idea to result is very important for the creative process.
Pro Visual editor
Pro Very performant
Being crossplatform it is important to work on low end devices.
Pro Easy and fast export for various platforms
Pro Great community
A very active and friendly community in forums.
Pro Source code available
You can download and modify the source code of the Editor and the engine for free.
Pro Collaborative
You can invite friends from the dashboard and create games together.
Pro Hot reload
It allows you to change scripts in a game while it is running live. Common use-cases is to tweak gameplay parameters or to perform debugging on a running game.
Cons
Con Learning curve for hobbyist developers
Hobbyist developers coding alone may experience a learning curve with Allegro of about 200 hours (if you are rusty on C++). To learn quickly, see Mike Geig's tutorials at Fix By Proximity. This learning curve may be fine if you are considering going professional, but are still unsure.
For hobbyist developers not planning on going professional, you may want to look into a complete 2D game engine, rather than a coding library. For example, there are "non-coding" engines that provide support for coded plugins or scripting. But, if you are a dedicated hobbyist planning to use Allegro as your coding library of choice, you can still develop great games as a hobbyist.
Con Isn't great for C++
If you are a fan of object oriented programming, and want to use this library, then the chances are that you are going to be creating a lot of wrappers for functions in this library.
In short, if you're a C++ person, it could be recommended to check out SFML instead.
