Well, I can't speak to the HVR-Z1U, as I have never used it (although I am a big Sony fan, and as they say, "No one ever got fired for buying Sony")...
But... I am a HUGE fan of the XLH1... I use it everyday. In fact, I am writing on a break from location shooting all morning with it, and am heading back out in moments to shoot more.
I love almost everything about this camera... in two decades in the business this has been my very favorite camera purchase (of any and all brands and formats). I can't say enough good things about it. Stunning picture, great ergonomics, and incredible ease of use. And to us, the removable lens is very important (I hardly ever shoot with the stock lens... in fact, if I wanted to, I would have to go look for it).
We bought one of the very first ones right when they came out, and it has been a real trooper... hasn't let me down once.
Fantastic Plastic Entertainment, Inc. fantasticplastic.com