I have the 50 f/1.4 ZE that I use on a 5D Mark II. It’s an awesome lens, great for portraits, shallow DOF, low light and landscape work with an unbelievable amount of detail. It’s small, well built and relatively cheap. I like to use a focusing screen made for shallow stuff, helps getting the focus right. If you’re in DSLR video, this lens is a must have. The focus ring moves a whopping 270 degrees (I think..) from infinity to min. focusing distance, making follow focus much, much easier.
An example:

I’m dreaming of the 21ZE for landscape work…
Cheers,
Jan