There are currently two java versions (vendors, if you will) available:
- Oracle's (Previously Sun) JDK, the closed source java, with commertial support from oracle 'n stuff.
- OpenJDK, the open source java. Oracle released part of their source and renamed it.
In the days of java6, there used to be a big difference between the two of them, OpenJDK running slower and supporting less, but nowadays, except for the java-web-plugin (Which was rewritten by the community and named icedtea-web), they are exactly the same. Neither of the two versions is "wrong".
There are still people claiming OpenJDK is worse than Oracle's JDK, but it's become a myth.
I recommend keeping OpenJDK for java7, because open source FTW, and because it's supported in the official repositories of ubuntu (Oracle does not let others redistribute their JDK).