For a list of SNMP frameworks for java, see SNMPLink.org
In my experience, for an open source, SNMP4J is the leader.
For a real compare you must try each one of them (not only reading) and see:
1. Easy and intuitive usage
2. You can accomplish all task you wish
3. Mark a special concept of the framework (if exists)
4. No-bugs
5. Performance
6. A live community
Other frameworks:
- WebNMS - commerical
- DynamicSNMP
- NetSNMPJ
Good luck and let us know of your results.