I use Iobit's program too and I like it. Haven't had the need to switch and don't plan to unless something happens with the one I have. I've checked the Auslogics one too and have the page bookmarked in case I ever need to change. Good reviews on that one.
Basically it comes down to personal choice. Try one for awhile, then the other and whichever you think you'd prefer, stick with that one. I don't know if either one is better than the other myself, but others might have an opinion.
If you like Iobit's Disk Defrag, you'll like their Advanced WindowsCare V2 Personal as well, which I also have.
AM CURRENTLY USING Iobit SmartDefrag Beta 3.1. VERY GOOD PROGRAM. CONSIDERING Auslogics DiskDefrag 4.1... BEEN CHECKING IT OUT ON CNET.COULD YOU ADVISE ME AS TO WHICH PROGRAM YOU WOULD RECOMEND. HOME USER. .TONY.