Under Disney canon, what does the Force ghost Anakin Skywalker look like? The 19 year old Anakin, before he was consumed and "killed" by Darth Vader, or the 45 year old un-Mustafar'ed version of Anakin had he remained in the light?
As explained here, when the updated versions of the films contradict the originals, the newer versions "win". Therefore, in canon, the young Anakin appears. Of course, a lot of purists will argue with this, but that's how it is by the rules of canon.
The problem here is George Lucas retconned the end of ROTJ to put young Anakin in, and remove old Anakin
So... which version is canon? Disney has more or less tiptoed around the issue. There's nothing anywhere that says which version is canon to Disney, likely because they would anger a ton of fans on either side. The last official word from Leland Chee, who was the original canon director, said this in 2008, when the Special Edition was the only one in release (emphasis mine)
Anything not in the current version of the films is irrelevant to Film only continuity
So, without a contradicting statement from Disney (which there doesn't appear to be one) the young Anakin is the canon version.