I have tried both Defraggler and Auslogics. Both seem about equal to me, both are free and both seem better than the one built in Windows.
I have also used O@O in the past and while they have many more defrag options than the free programs I do not believe it is worth paying for a program like this with the others being so good. I actually got a free key from O@O as a special but it was for a version ( 10 maybe? ) that only worked with XP. That does not help since I do not run XP anymore so I never used it.
Pretty much everthing from these guys is useful. Speccy is better than CPU-Z.