DK10 Pro, with i-faast...HANDS down better than perfectdisk. Believe me, i have my reasons. I was a PD supporter too for many years.
I could list points now why DK10 is better....starts with filemonitoring and layout of files depending on how frequent they're used.
http://www.diskeeperblog.com/archives/2006/09/inside_ifaast.html#more
UNLIKE what PD says that DK uses "last time accessed" (or "modified", whatever)....in fact DK uses "last accessed" only for the first ever run of ifaast...but then continues to monitor usage and lays them out depending on "most used".
So..either one lies..either PD stating lies about how DK's iffast works..or DK just plain lies about DK's features, which i dont think
Besides DK does something very great, it does NOT consolidate ALL free space "at the end" of the HD liek PD does.
Figure a HD like mine which is 90% full - the last 10% (the free space) would be 50% slower in raw MB/s...you canmeasure that with tools like HDtach etc....EVERY HD starts out fast 'at the beginning" and usuallty the rates drop 50% or so at the end of the HD.
DK actually always creates free room in the first THIRD of the HD.....so basically even if you use your HD for years, over the years the performance of newly created files and write-accesses is GOOD.
NOT with PD.....it holds ANY free space at the end....and when your HD gets full in time every WRITE access and newly created file is SLOWER because it happens at the slow end of the HD ! It literally degrades your performance !
Want more reasons why DK is better ???
btw i just see there is a new DK out
(and NO, i am not a scientologist but DK *is* the better defragger