Harry Kanterman medal 5000 219 days ago
Every manager views this differently, but I would say that in order of importance, the highest priority buildings are Design, Tech, YDA, Simulator, Manufacturing, and Offices and Hospitality at the bottom.
Considering your level, I would get your manufacturing to a sustainable level, then focus on getting design and tech to as high as your level allows. From there, I'd start working on the YDA and simulator sparingly, while still upgrading design and tech. The O&H is great in the long term, but the other 5 are more important in my opinion.
The YDA is very important at high levels, but considering you're still level 6, the transfer market should be fine for now. I'd hold off with it until the other ones are developed well first.
I hope this helped!