Code Igniter vs Laravel

Things CodeIgniter does better than Laravel

1. It's a bit faster maybe
2. Lower learning curve (not necessarily such a good thing, see the huge amounts of terrible PHP out there.)

Things Laravel does better than CI

1. Routing, big time.
2. Has an ORM
3. Has a templating engine.
4. Abstracts the request cycle
5. Dependency Injection
6. Set up for testing (4+5)
7. Proper CLI support which allows for e.g. work queues out of the box
8. Migrations that work
9. Composer
10. Doesn't abuse globals in the CI style (though there's maybe some sneaky singletons and static calls going on in there)
...

Routing especially wins it for me, CI's router is a bit of joke really. Routing to classes/methods automatically based on the url seems like a good idea until you realise it results in very tight coupling between urls and implementation, which are two things that have no business being together. I think automated routing is bad idea generally as it encourages you not to think about what you are doing.

Because CI predates the popularity of autoloading / doesn't really do autoloading, you have a related problem in how the router actually decides what class to load. It loops through your controller directory, looking for a class name / method name combination it can call. It is limited in how deep this directory structure can go (I think you can go one more dir under controllers without having to rewrite part of the router), and obviously has no support for namespacing. The result is you either get a huge number of classes in the global namespace all sitting next to each other (sort of annoying) or huge classes with huge methods (terribad), because the architecture of the framework neither enables nor encourages splitting things up. You can quickly end up with huge technical debt because the way CI handles the request cycle almost forces you into anti patterns.

Add on top of this the fact that the framework doesn't finish bootstrapping itself until it has decided which controller its routing to and you're ready for a bad time.

I could go on....