For applications where prospective students upload transcripts, is there a preference between scanned official vs unofficial transcripts? It is my understanding that most graduate schools will want you to mail them a sealed transcript if accepted, but my question is about the application process.
I thought that I could upload an unofficial transcript that I retrieved from the school's web portal, but after some more investigation it appears that maybe I should upload a scanned copy of an official transcript.
Of course an official transcript is no longer official once it is unsealed.  But do graduate schools prefer it that way?  The answer might vary depending on the department, but I think a scanned version might be the safe bet.  Although, it would require a bit more effort on my part to request an official transcript.
Edit
I should have included this originally, but I didn't want to make the question specific to one school.  But this school is specific about wanting a scanned copy, whereas others are not.  I'm just wondering if it should be assumed that a scanned copy is preferred if not made explicit.
From FAQ:

Do I need to mail hard copies of official transcripts in addition to the transcripts uploaded with my application?
No, simply upload a scanned version of an official transcript that has been &quot;Issued to Student.&quot; It is understood that once you open the envelope to scan the transcript it is no longer considered official. It may also be possible that the scanned copy may have the watermark COPY on it, which is fine. Do NOT mail transcripts to the Department nor the Graduate School unless asked by the Department to do so.

Obviously, if I were to apply to this school I should use a scanned copy, but it's what caused me to reconsider if this is really what other schools want as well even if they don't state it explicitly.
If an "unofficial transcript" is requested, generally they just want something that contains the relevant information: courses taken, grades, any disciplinary sanctions, etc.

It might be most convenient to scan an official transcript, because then it will be in the most familiar format, but as far as I know it is also fine to, for instance, retrieve your own records from your university's system and print the relevant pages to PDF.

On the other hand, transcripts are usually printed on special paper that causes words like "COPIED" or "VOID" to appear on any copies or scans that are made.  Of course if the department only wants an unofficial transcript, they should not care that it is a copy, but sometimes it's hard to read a transcript if it says "COPIED" all over it.  So whatever you send, make sure it's legible.

Of course, as you say, an official transcript (sealed, by mail) will usually be demanded if you are accepted and/or decide to attend, and woe be unto you if it does not match the unofficial transcript you provided with the application.

It can't hurt to contact the department and ask what they would prefer.