At 70 C, you're running it way too high (AMD's official limit for Phenom II's is 62 C).
Best watercooling solution is the solution that has lots of large radiators plus the best waterblock available (Apogee XT Rev 2, EK Supreme HF, Koolance CPU-370). Really, watercooling has too many variables to suggest a "best."
Better cooling? Phase change, check out the extreme cooling section.