The 50L is a wonderful lens at every aperture. It's rather 'artistic' between f/1.2 and f/2 due to the shallow depth of field. The 50L is also heavy and rugged along with expensive. If you just want a 50mm lens, the f/1.8 lens is everywhere as good as both the more expensive lenses from f/2.8 onward. Saving $1000 with the f/1.4 still gives a solid lens, and much more sturdy than the f/1.8. Consider your "true" needs in the f/1.2 to f/2.8 range as the f/1.8 is an excellent lens, and don't let it's price fool you into thinking you need to spend more unless your need for f/1.2 to f/2.8 is the reason to spend more.

I've also used the Zeiss Makro-Planar T50 f/2 ZE. It's a manual focus lens, but does give a focus confirmation. It has an excellent image quality at f/2 onward, both colors and sharpness. It's heavy too being all metal and glass. The unique image characteristics, again in the f/1.2 to f/2.8 range, would be reasons to choose one of the more expensive options over the EF 50 f/1.8.