Abe, I've been in the same pickle as you are. I was stuck between the exact same cameras. I'll share with you my findings.
First of all, I've heard a lot of recommendations of the z1u over the FX1 because of its pro features.
One big factor the decided it for me was that the XL2 has a better capacity for a cine-like feel, while the Sony is great for documentarian style work with it's great color. However, I hear that XL2 captures motion better than the Sony.
The Canon has the ability to change lenses, which is great if you want to do more with your work visually.
The HD will supposedly transfer to film a lot better if you are wanting to blow it up for a big screen, like for festivals, etc.
FINALLY, I'll share with you my conclusion. I have decided to go with the Canon. I want a good all-around camera, and I'll be making more story-based films than documentarian or videographer work, so a better capacity for good-looking moving shots is more valuable to me. Though I lament the loss of HD, I am comforted by 28 Days Later, a film shot with the XL series. Also, I'm going to be working on a project for the Discovery Channel with some friends, who are shooting on an XL1, and what they've made so far looks great. Lastly, I've always treasured content over superficial quality. I think a film can be great without it being the best visual quality, period, you know?
It's really all in what you personally want. I don't think you can go wrong with either of these. But, what do I know, I'm only a student and a cinematography.com newb.
I hope I've been of help!
You should also look into the DVX100 by Panasonic. It's shaped more like the Sony, and it is optimized for 4:3 ratio, while the Canon is geared toward 16:9.
I hope I've been of help to you!