I use O&O Pro, and it is sweeeeeet. Set it and forget it... it defrags when you need it in the background without slowing you down.
It's nice to have 0% fragmentation...
Here's trial versions of each:
|MG| Diskeeper Professional Edition 2008 12.0.758.0 |MG| PerfectDisk 2008 Build 39 |MG| O&O Defrag Professional Edition 10.0.1634