I think the Palm platform has the most variety of Bible readers available with many different versions. The PPC is limited to a few readers with fewer choices in flexibility.

It really boils down to what you want in a Bible reader and which versions are available. In the end - it is down to personal preference and "fit for use".
I am glad that I can carry a copy of the Bible with me (plus dictionary, CIA world fact book, thesaurus, idioms dictionary and references...) it makes my Palm PDA a very flexible instrubment to use! :)