Unless Neoclipse has some code that requires Java7, I'd say go for oraclejdk6 for 1.9 series and oraclejdk7 for 2.0 series (when we get that far), which is what Neo4j has as it's primary Java platforms.

Don't think building against openjdk makes much sense, when there's no tests to execute! (the code in there is just some small examples, no tests)