What is the most respected (useful, understandable) XML Java package?

In a few fits of creative rage, I have managed to write my first Java
programs. I can now index plain text files with Lucene and search the
index. I can parse MARC files with MARC4J, index them with Lucene,
and search the index. I can dump the results of the OAI-PMH
ListRecords and Identify verbs using harvest2 from OCLC.

I now need to read XML. Unlike indexing and doing OAI-PMH, there are
a myriad of tools for reading and writing XML. I've done SAX before.
I think I've done a bit of DOM. If I wanted a straight-forward and
well-supported Java package that supported these APIs, then what
package might I use?

(Now if I could only wrap my mind around reading those JavaDocs.)

--
Eric Lease Morgan