Lines of code is obliviously not a benchmark to rank a micro framework.
The term "mirco" refers to the amount of functionality the framework exposes. Often a micro framework is just a router decorated with some other useful stuff. Who cares about lines code, especially when you count "all" dependencies in vendor.
- BulletPHP: 3946 lines of PHP code
- Slim: 7329 lines of PHP code
- limonade: 3669 lines of PHP code
- Lumen: 95'220 lines of PHP code
You can't call it a micro framework if it's more than ten times bigger than all the other ones.