The A1 and Z1U are extremely similar. The Z1 is much more expensive, but you said price isn't a factor. Z1U's main advantage at least in the global market, is it's ability to shoot PAL and NTSC, but for most applications it's not useful.
I personally think the XHA1 uses a better HDV codec. (no pixel shifting) Also, if you want to shoot 24 fps, the XHA1's 24f mode (full frame) is a better system than sony's CineFrame 24. Both are interlaced signals with flags and pull down, but Canon's 24f has been accepted by the filmmaking community as being comparable if not identical in appearance to Panasonics 24p.