OK ... Before we get too far into this we need to figure out the scope of the project. In the showreel will their be graphics and cool/custom transitions then I'd recommend (I know I'll regret this) After Effects. If it's straight cuts and cross dissolves the FCP or Premiere route is the way to go.
Now to answer your question of how I would make it ... Being a mograph designer I'd rough the thing in FCP and make motion elements in AE/C4d, then finish the comp in FCP.
FCP and Premiere are faster in the sense that they are strictly linear editing systems (you can do basis "graphics") and once they render a file you have alot more control as well as viewing power immediately. AE has a nasty habit of having to render the frames at the smallest change and it takes forever to get a view at fullres sometimes. FCP will convert the video to a codec (if you set the comp to that codec it doesn't have to, therefore not as much rendering) so once its rendered you can view it at full in about a 1/10 of the time. Also the timeline is different, in FCP you can have multiple clips on one video layer, whereas AE everything has to have its own layer ... I could go on and on (and stop rambling
)
Most workflows involving FCP and AE usually involve making a rough concept and getting the timing so you can make your assets in AE. Once those are completed you export your QT, Image Sequence,etc into FCP and in a linear environment splice them together. For the most part if you know what your doing AE and FCP play very well together. I work with both on a daily basis and I don't really have alot of issues.
I know I might have rambled in this and I may not have answered your question to your liking but its a very broad subject and depending on the goal every solution in unique.
Hope this gives you a starting point
~Florio
