Full Frame vs. APS-C

Tossing up between the A7sii vs. a6500. I like both cameras a lot and have used both. The sensor size is really the only factor deterring me from the a6500. I plan on building out a kit and am concerned that investing in an APS-C camera will limit me when I upgrade later on since I would like to buy a few lens. The intended purpose for this kit is filmmaking, mainly shorts and music videos.

Any advice or thoughts would be really appreciated!