which macbook should i choose?

I'd start by looking at the technical specs for each of these models you are interested in:

• MacBook Pro (Retina, 15-inch, Early 2013): https://support.apple.com/kb/SP669?viewlocale=en_US&locale=en_US
• MacBook (Retina, 12-inch, Early 2015): https://support.apple.com/kb/SP712?viewlocale=en_US&locale=en_US

Then review both the minimum and recommended system specs for each app you want to run on these Macs to make sure that they can support the latter ... and still have some room to spare.

Since you plan on using it for film editing, I would think the larger screen size will come into play in the long run.

The other thing to take into consideration is the repair potential and what Apple will still provide parts for. Both models are still listed as "Supported". The next stages go to "Vintage," and then, "Obsolete." The following article should explain Apple's support designations: Vintage and obsolete products - Apple Support

For reference, Apple discontinued manufacturing the Early 2013 MacBook Pro in October 2013 and the Early 2015 MacBook in April 2016. That would mean that the MacBook Pro is soon to fall into the "Vintage" category ... which would mean you would not be able to obtain any form of hardware service (unless you plan a trip to either California or Turkey ... go figure!)

You're very welcome! Enjoy your "new" MacBook.