So we went out and played with 50mm lenses today:
canon 50mm f1.4
Sigma 50mm f1.4
(canon 50mm 1.8 was dismissed on build and canon 50mm 1.2L were dismissed on poor build quality/cost.)
The Zeiss was dismissed on non AF grounds, even though IQ looked very good. I have to say the AF of the Sigma we tried was possibly the worst I have ever tried. It was a display copy, I realise it's probably had a lot of use and isn't as good as a lot of people have, but it really was all over the place and as a result the Sigma was passed over.
The canon f1.4 really suited my friend, the AF was great, the image quality awesome,he picked up an immaculate 2nd hand copy for a great price, we went out and tested it more and he was over the moon.
Thanks for the input everyone, I really appreciated it. We tested out as much as possible based on what I heard and my friend based his decision on what we tried. Had it been a better Sigma or a not so good canon it could have been a very different result, but with what we tried it was was it was.