I received an Email from "Tom's guide" informed me that I have a reply from a user called "Lianbogdady ", and when backing to the thread I didn't find any reply to my question, I found that the reply sent to my mail sounds good and logic, I will copy the reply from my mail and past it here, I think it will be helpful to the others.
This was the reply
"
The following is the best practice from it's forums:
Copy changes only to be selected, if the destination is empty then it would copy everything.
Then right before cutover, switch to mirror as mirror would remove files from destination that users deleted from the source over time. This makes the destination to be an exact replica of the source.
Copy all files is there for customers that want to copy all files every time and not skip existing files that did not change due to company policies or regulations.
Copy changes only and mirror would copy new and modified files but skip unchanged files. Mirror goes the extra step to sync deletions from source to destination."
Thanks