When comparing MonoGame vs PICO-8, the Slant community recommends MonoGame for most people. In the question“What are the best game engines for point & click adventure games?” MonoGame is ranked 5th while PICO-8 is ranked 38th. The most important reason people chose MonoGame is:
Support for iOS, Android, Mac OS X, Linux, Windows (both OpenGL and DirectX), Windows 8 Store, Windows Phone 8, PlayStation Mobile, PlayStation 4, Xbox One, Nintendo Switch, and the OUYA console with even more platforms on the way.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Cross-platform
Support for iOS, Android, Mac OS X, Linux, Windows (both OpenGL and DirectX), Windows 8 Store, Windows Phone 8, PlayStation Mobile, PlayStation 4, Xbox One, Nintendo Switch, and the OUYA console with even more platforms on the way.
Pro Open source
All the code is available to you ensuring you'll have the ability to make changes when you need to or even port to whole new platforms.
Pro Well-known and documented API
The framework implements the XNA 4 API, so games made in XNA can be ported to other platforms using this. This was the same API used by the Xbox Live Indie Games platform so there's lots of documentation online for it.
Pro Managed code
By leveraging C# and other .NET languages on Microsoft and Mono platforms you can write modern, fast, and reliable game code.
Pro Good community
The community MonoGame has to offer is helpful and mature.
Pro Performance on desktop
The performance on desktop platforms matches that of C++, but you still get all the pleasant features that C# has to offer.

Pro Takes away the pain of having to wire things together
Because it's an all in one product, you don't have to worry about things like how to load sprites.

Pro Very simple programing language
It's lua with a few modifications.

Pro Encourages building simple games
As a beginner it's all to tempting to try to make the games you like to play, like Zelda or Call of Duty when we should probably be making pong.
Pro Restrictions of tokens count "forces" to write code effectively
When you reach 8192 tokens, you're screwed. However, this limit can teach you to take a look at entire code and think how you could optimize it.
Pro Possible writing code in external editor
Since launch of 0.1.12c version of software, you can now write and include external script using the same directive just like in C / C++.

Pro Perhaps one of the easiest sound editors around

Pro Share the game in a .png file with other Pico-8 users

Pro You can read the code of any game you play

Pro Lots of examples
Almost every game made for the Pico-8 is open source (if you can download the .png, you can see the source).
Also there's the fancy Pico-8 "fanzine" that has lots of code examples as well as other great tutorials in a beautiful physical or PDF form.

Pro Easy to get things going very quickly
Cons
Con Slow rate of updates
Versions 3.9 is overdue by a year, and version 4.0 is set to release in 2040.
Con Non-Windows tools are a bit funky
Monogame support for Xamarin Studio or Monodevelop is a bit shaky especially for library references. Only good non-Windows IDE compatible with MonoGame is Rider and that costs money & isn't open-source.

Con No collision library or other common things
Pico-8 is very minimalistic and as such doesn't come with really any abstractions whatsoever which means often you end up re-inventing the wheel.

Con Code editor leaves some things to be desired
Such as code completion and automatic indentation.

Con Costs 15$
Unlike many of the other frameworks it's not free. However this is kind of a feature because it means it's much more likely to be supported.

Con Memory restrictions could be confusing or frustrating to a beginner
