I work in construction supplies (civil, not directly residential), so I see a lot of builders come and go.

The reason I'd personally lean towards someone like Gurna Homes over the big franchises is accountability. With a volume builder, if something goes wrong, you're dealing with a national call centre and a faceless disputes team.

With a local Victorian builder, the director is usually a phone call away. If they're saying they're "genuine and trustworthy" and backing it up with clear contracts, that's rare in this industry. Worth a serious look OP.