What are the Essential Lenses for DSLR Filmmaker?

I've been Making short films and mini-documentaries for a while now, I currently own a 600D that i'm cuerntly learning with, the camera has a cropped sensor, which means when buying lenses I have to become aware of the crop ratio, other than the stock lens that comes with the camera, I've recently bought a 50mm, as everyone seems it's an essential. I couldn't agree more, but it seems to over do it for me. after time passed i bought a few lenses, but what i found myself using the most is the stock at 18mm, using a 35mm, and 135mm. I find these lenses brilliant to use. my question is, what other lenses have you tried? what did you like or hate about them? and what do you recommend?