It really comes down to a choice of using Mac OS X with a focus on the Mac side or the Unix side of things.
HFS+ is the choice for Mac users. A lot of meta-information about each file is preserved. File name capitalization is preserved, but the system doesn't see a difference if you want to use "My Report" or "my report" which is what most Mac users expect. It's also the more compatible format if you're going to be going back and forth between Mac OS 9 or you want to have better compatability for the Classic environment.
UFS has it's good side, but overall it's the type of file system that meets a Unix user's expectations. It is fully filename case sensititive. It preserves virtually no extra metainformation about a file. It isn't viewable by Mac OS 9 and may give some Classic apps problems.
If you come squarely from one camp and want to "test the waters" in the other, I'd suggest making the boot partition be HFS+ and have another partition that's UFS.
Most Mac users will probably stick fully with HFS+