When comparing Crafty.js vs Leadwerks Game Engine, the Slant community recommends Crafty.js for most people. In the question“What are the best 2D game engines?” Crafty.js is ranked 37th while Leadwerks Game Engine is ranked 75th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Javascript

Pro Eventbinding
Easy to learn, based on Entities and Components, the later being class-like objects that entities inherit.
Pro Modular
Has open function binding systems, allowing easy creation of custom components.

Pro Versatile flow diagram script model
Leadwerks's flowgraphs resemble flowcharts where each box represents a function or value, with connections between them representing program flow. This provides a better at-a-glance indication of game logic than a simple list of events, and makes complex behaviors easier to accomplish.
Pro Built-in level editor
Has an acceptable 3D map editor that is easy to use.
Pro Handful of Prefabs and Scripts
For example, you take a model (e.g. torch), add a light source to it, add a particle generator (for fire) and save it as a prefab (one file). Then this prefab can be used to add many torches with fire and light.
Cons
Con No IDE
If you like having some huge GUI akin to Gamemaker, Unreal, Unity, etc, Crafty is not for you.
Con Very buggy
Leadworks is a not complete, it's a work in progress. As such many parts of the engine are clunky, especially the level editor.

Con Documentation and support are limited for non-coders
The flowgraph editor can be used with free script assets to build games without writing any code, but this is not directly intended or encouraged by Leadwerks.
Con Highly misleading advertising
