When comparing LightDM vs Slim, the Slant community recommends Slim for most people. In the question“What is the best Linux Display Manager?” Slim is ranked 1st while LightDM is ranked 2nd. The most important reason people chose Slim is:
Slim's documentation is well organized and detailed, every concept is thoroughly explained and it is very helpful for both advanced users and beginners.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Beautiful interface
Some greeters such as the Unity Greeter look absolutely beautiful on LightDM.
Pro Best balance
Best interoperability, best balance between functionality and bloat, simplicity and candy, not distribution or GUI-tied.
Pro Cross-desktop
LightDM is not tied to any distro or desktop enviornment. You can use it on literally any Linux GUI.
Pro Good for DEs without a display manager
If your Linux desktop does not offer a display manager, you should use LightDM.
Pro Theme variety
There are a wide variety of themes available for LightDM, from console-like UIs to ones that utilize webkit2 to create flashy and dynamic login interfaces.
Pro Well organized and thorough documentation
Slim's documentation is well organized and detailed, every concept is thoroughly explained and it is very helpful for both advanced users and beginners.
Pro A good starting point
Slim is minimal and that is a good thing if you want to start from there. It can be easily extended and even supports popular packages that are used in Laravel (like Illuminate\Database (eloquent)) for example.
Pro REST based
REST fans will love the REST based architecture.
Pro Supports tie-ins for Rack-like middleware
Rack is an interface used in Ruby frameworks used to group and order modules, which most of the time are Ruby classes, and specify between them.
Slim uses a simple concept for it's middleware. By wrapping HTTP requests and responses it unifies the middleware into a single method call.
Pro Useful classes
Contains classes for managing requests, responses, cookies, logging, views, HTTP caching, and more.
Pro Flexible
Slim doesn't demand that you stick to a fixed folder structure. As long as you load Slim the right way you can do anything from there the way you like it.
Pro Extremely lightweight
Paired with swoole it's a micro service powerhouse.
Pro Open source
The Slim Framework is open source and is released under the MIT public license
Pro Extremely customizable
You can add any dependency, package or class that you want to use as a contained dependency.
Pro Supports Php 5.3 and PHP 7
Pro Makes it easy to understand the way some abstract functions and classes are built
In Django most things are abstracted, you just call some function or class without knowing how they were built, but with Slim, you end up understanding the way some abstract functions and classes are built.
Pro Hooks for executing code at different points in its life-cycle
Slim supports code hooks for executing functions at different points in time during the application's lifecycle.
Cons
Con Not really lightweight
How lightweight it is depends on the used greeter, but they all require much more dependencies than other lightweight greeters like XDM or SLiM.
Con nVidia driver and kernel woes
It's been on the decline lately where it's only stable under a very specific mix of kernel and nVidia drivers.
Con High RAM usage
It uses more RAM than other light (xdm,slim) display managers which results in more overhead.
Con Poor/missing documentation
Con Hard to configure
Lighted.conf doesn't even work.
Con Autologin never worked
After 4 years of using LightDM, I never managed to make it autologin my user in the system and there are always problems with the graphics driver. Crashes too often and requires manual restarting which is dull. Not to mention the developers update it once in a leap-year.
Con Feature creep
Most people don't need (or even know) all features of LightDM.
Con Very little consistency among different versions
There have been quite some changes that break the compatibility between Slim 2 and Slim 3. Even if you learned how to work with the Slim 2, you will find that Slim 3 requires re-training.
Con Dependency injection is too weak
It is not really dependency injection, but just a configurable container.
Con Needs strong bases to create dependencies
The dependency container schema of Slim is one of the biggest PROS and CONS of the framework. It is true that this schema brings so much flexibility to add anything, but another thing that is true is that you need to have strong bases of patterns, and an extensive knowledge of your libraries to convert it into a Slim dependency.
Con Too minimal
While it's true that Slim is a microframework, it's still too minimal. When used for throwaway projects or simple prototypes, it's perfect. But in the long run, it becomes less and less useful and you end up in implementing a full custom framework in trying to tackle all the missing features.