I found CodeIgniter to be really useful for a self-taught, spaghetti-style PHP programmer. It is the only framework that most such programmers can grasp by themselves using tutorials and docs available online. Any other framework, and they would require a lot of hand-holding.

Switching from CI to something better later is really not that hard and it's much, much easier that learning one of the modern frameworks from scratch.

I'm talking about self-taught begginers without CS degree or working-in-a-large-team experience.