For me it was the Sternglas Hamburg. I know its not such a well known company but it was the very first mechanic watch I bought and owned. 

For a looong time I just couldnt understand why people keep spending many houndreds and thousands of euros/dollars on watches. I liked watches but I couldnt see this fascination with them.. 

When I saw the Hamburg I began to dive deeper into the topic of mechanical watches and now I own it and Im so fascinated by this technology, it will be for sure not my last mechanical watch.. :D