I used to sell cameras and video cameras part time for Fry's Electronics a few years ago. I can tell ya the last one you don't want. The biggest reason is it shoots to a memory card. A 4 gig Memory Stick Duo on the cheap side is around $50 or more. Not sure how much video you can hold on a 4 gig card but I bet its not a lot, an hour at most. So you'll have to buy a bunch of them. Imagine going on a weeks vacation, now you have to carry a laptop with you to download your video. Pass. I am a geek. True and true, but the last thing I want to take on vacation any more is a laptop.
The other Sony, the HDR-UX7 uses both memory and DV tape. If you can shoot to HD-DV tape great, but if it only shoots HD to memory than I'd pass for the reasons above.
The XL1S is really a semi-professional/professional camera. To be honest, I think you'd wind up with about the same quality of picture. The mini HD cameras have small CMOS sensors and they are pretty good especially if they do 720p or 1080i but I think the 3 CCD on the Canon and the MUCH better lens more than makes up for it not being HD. I mean, the Sony has Zeiss lens but they are kind of small where as you get a nice big lens (that can be changed out to use different types of lenses) on the Canon that's much better.
Then, ok, when you're done. Where ya gonna put your movie? Do you have a Blu-Ray DVD burner? If not add that $400+ to your cost if you buy the Sony otherwise the only way to output to a true HD is to play it from the camera itself or your PC. If you want to share it, you're going to have to burn it to a regular DVD and then you lose the HD resolution anyway.
For the money I don't think you'll go wrong with either of them as far as quality but if I were buying I'd go with the Canon for now. Once the Blu-ray/HD war settles down and the cost of burners (and the disks) come down than it might be worth it. But by then newer, better cameras will have come out and by then you might be in the market for a new camera anyway. Just my 3 cents.
Cheers
Rob
The answer is always "PEBKAC!