Well, I've tried all 3 of them (I used to use O&O Defrag v4 - Excelent defrag) and my comments are:
O&O v6: Seems like a downgrade from version 4; It seems to have less features available.
Diskeeper 8.0: Did not suprise me; defrag speed was nothing special, and it felt like there could be more space for improvment
Perfect Disk 6.0: Well, this one was a suprise! It was fast (not as O&O v4) and the boot-time defrag was one of the best I've seen! While the others (including O&O v4) reported that there was little or no defragmentation on pagefile, MFT, etc..., Perfect Disk took almost 15 minutes to complete boot time defragmentation. I know this probably means nothing, but I want to believe (until someone proves me wrong)
VoptXP: I tried it once didn't like the interface. And after reading so many things about NTFS and this prog, I decided not to give it a go! Sorry to all VoptXP fans out there
