I think it really depends on the person and what they're looking for, or willing to put up with in some regards. I think it can be most easily separated into chunks.
Original or Remake are the best entry points, depending on what type of games the person enjoys tactically. Original should be played right after remake at the very least, but Remake can be saved for last if original is played first.
Advent Children is probably the next litmus test as to how much deeper the person may wanna go into stuff, as its a pretty low-commitment watch. They can read the novellas before or after, depending on what their preference is really. Personally, I think the movie is confusing enough to create motivation for reading the novels for things to make sense, while I don't think the novels are really interesting enough to make up for the potential deflation at having to read a bunch of stuff to contextualize a silly shounen movie. That's just me though, I'm sure there are many who wouldn't be put off by going through the novels first.
From there, it kind of branches off depending on where their priorities lie. If the person didn't go through the Remake entry point, I'd save it for after Crisis Core. DoC/BC can be delved into whenever.
I don't think there is really a hard pipeline for everything to "flow" nicely tbh. The closest thing is order by release, as it gives the most cohesive evolution as to how the dev's thought process evolves.
