If we decide to go with a quadcopter geometry, for the initial prototype I'm selecting the Tarot TL280h frame. It is a couple of years old racing frame which is actually a good thing. A few years ago components were much bigger and since we'll need to fit sensors, companion computers and a lot more on a single frame, we need the space. Modern frames are very minimalistic and offer very little in terms of real estate.
The Tarot is also made to have an external shell which means we can design our own a lot easier since we have dedicated mounting points. As the project evolves and our components get streamlined, lighter and smaller we can design a brand new custom frame, reducing the overall aircraft size and weight as well. All in all, the Tarot TL280h is an excellent platform to start with.