28mm, 50mm and 85mm, sometimes I need something wider or sometimes narrower, but those three are definitely the focal lengths I use the most.

I use Nikon AI - S lenses myself, I have the 28mm 2.8 and 50mm 1.2, and I love them.
Here´s a trailer for my last short film where most of the shots where done on those lenses:
https://vimeo.com/115880865

For me film school was a great way to start learning the field, but what makes the difference is how you develop what you learn there further. So even if you go to film school you have to eventually become self - taught to progress, but you will most likely have a much better starting point if you attend a good film school.

This has been the experience for myself, anyway.

I can warmly recommend the Nikon AI-S lenses, I use both the 28mm f2.8 and the 50mm f1.2 on my GH4 with a Metabones Speedbooster, and I love them, the 50mm was used for about half the shots on the short film I'm currently working on, I got a teaser here if you wanna see what kind of look the lens gives: https://vimeo.com/111116514 (All shots except for the third shot and the wide shot at the end was shot with the 50mm)