When people speak of transfer I find they mean one or more of three things
1) All their documents, pictures, videos and music*. Back when, and for my personal setups I still can, I used to just stick the hard drive in my external reader and press copy to wherever it needed to go, I might have also installed a FTP server and transferred that way. These days windows will actually take note of file permissions and owners, I usually link people to something like
http://www.faqforge.com/windows/take-ownership-of-a-file-or-folder-by-command-in-windows/ for these instances.
Depending upon how you do it you will come to know the truth of
https://xkcd.com/1360/
By and large I find any kind of windows transfer, restore or backup functionality to be fine in certain lab tests and very specific scenarios. For the real world and average desktop computer user I would not trust it to do anything and that definitely includes trying to transfer to a new system, let alone a new OS.
*shakes fist at itunes. It can make things a tiny bit more complex but should not get in your way too hard and worst case for most if they have to rescan the whole library at however long that takes. Do also not idevices are occasionally limited in the number of devices they can be managed by so you may have to deactivate one or more if you are planning to retire a machine.
2) Their browser and email settings. Bookmarks, adblock lists, history (many browsers combine history and bookmarks these days after all). Some modern browsers will allow you to sign in and share tabs and bookmarks wherever they may be, personally I would not touch that if you paid me so I get to manually transfer things across.
http://mozbackup.jasnapaka.com/ does well for me here. Do note you can also do things like use chrome or firefox's import data from other browser feature to pull things across, set up on a new machine and then pull back if one or the other is giving you hassle.
Another little tip I picked up. Some people use the autocomplete on various versions of the outlook email client basically as their address book. The format that handles this is NK2 and can be looked at and bothered by
http://www.nirsoft.net/utils/outlook_nk2_edit.html
3) Everything else. Windows has been going for many years at this point and was seldom all that bothered about how programs behaved a while back and is not great for it now. To that end you have a thousand different ways for programs to store data, settings and more besides. Trying to migrate with such things is a nightmare so most don't do it unless the program maker/devs specifically have a guide or they know what they are doing or they only want some specific things. That said there are things like
http://mirinsoft.com/ nowadays which you can try.
Final tip. When you are on the new machine and dreading having to download and install loads of things then make sure it is not on
https://ninite.com/ before you set about it. It is a great little program which installs all sorts of programs with all the good settings (no toolbars and the like).
