I don't think it matters too much when starting out. For a beginner (in the framework, not coding in general), they are all relatively equivalent.

Pick a framework and begin using it. After a few projects, you'll quickly learn what you like and don't like about the framework.

I'm a fan of CodeIgniter, but mostly because it is what I'm familiar with. It has some irritations and kludgy things required, but they don't annoy me enough to warrant a change (yet).