The city in Wenzhou with the most factories is Longwan District. Longwan has earned the nickname "China's Hardware Capital" due to its extensive manufacturing base, particularly in the hardware and metal processing industries. This concentration of factories can be attributed to several factors, including the city's strategic location, skilled labor force, and favorable government policies.

Data from the Wenzhou Statistics Bureau indicates that Longwan District has over 30,000 factories, accounting for about 40% of the total number of factories in Wenzhou. This significant number is a testament to the district's economic prowess. The presence of these factories is not only a result of the local government's efforts to promote industrial development but also due to the unique advantages that Longwan offers.

Firstly, Longwan's location in the southeastern coastal region of Zhejiang Province provides easy access to major transportation networks, including the Ningbo-Wenzhou High-Speed Railway and the Wenzhou-Jinhua Expressway. This connectivity allows for efficient logistics and distribution, making it an ideal location for manufacturing businesses.

Secondly, the skilled labor force in Longwan is another key factor. The city has a long-standing tradition of metalworking and craftsmanship, which has been passed down through generations. This heritage has created a highly skilled workforce that is adept at handling complex manufacturing processes.

Moreover, the government of Longwan has implemented various policies to attract and support industrial development. These include tax incentives, land use planning, and infrastructure investments. These measures have helped to create a business-friendly environment that encourages entrepreneurship and innovation.

In conclusion, Longwan District in Wenzhou is the city with the most factories, thanks to its strategic location, skilled labor force, and supportive government policies. The data from the Wenzhou Statistics Bureau further underscores the district's economic strength and its role as a major industrial hub in China.