Best orm on the market.

Most of the time, I can forget that the database even exists. I'll just draw/modify my UML class diagram and have the M[odel]Driven framework create/update the database schema for me. I mostly work in an object space (a RAM cache) as if everything was already there, using object oriented OCL instead of SQL. In a GUI, I could databind to it too, using regular data aware components. There is kind of a steep learning curve, and the documentation could be better.