What Should First-Time Buyers Look for in a Builder?

I'm currently researching several pre-construction communities across the GTA, and I'm finding that comparing builders is more challenging than I expected. Marketing materials usually focus on designs and incentives, but they don't always reflect the overall buying experience. When researching Toronto home developers, what do you consider the most important factors? Do you look at completed projects, warranty coverage, construction quality, customer reviews, or how builders handle delays and communication? I've been comparing information from different online resources to better understand builders, project details, and community information before making any decisions. Even so, I'd rather hear from people with real experience than rely only on listings or promotional material.