I can't decide which to get?!? (the zeiss 1.4 is another 500 more than the canon so it has been excluded)

I have been scouring the net for reviews but not really getting any great comparisons (all very one sided). Essentially this lens would be used for group portraits at events, weddings and possibly in some fashion/general portraiture (in tight spaces or where I want to exaggerate space a little. Plus, some landscape shots... Gee I'm not asking for much :P

Does anyone have any insights/examples as to which is the superior lens? Or is it a much of a muchness kind of thing (I don't mind manual focus and I'm aware the zeiss is slower but I can use a speedlight to compensate)

Ooh and I'd be using it on a 5D Mark II