Meanwhile, Shenzhen spent 5 percent of its GDP on research and development in 2013, while Guangzhou spent just over 1 percent, he added. There are more than 58 invention patents for every 10,000 people in Shenzhen, six times that of Guangzhou.

Moreover, Shenzhen filed more than 10,000 international patents under the Patent Cooperation Treaty in 2013, more than any other city in China and representing 48 percent of the country's total.

The 2015 City Momentum Index released by international real estate services provider JLL in February showed that Shenzhen might have also overtaken Shanghai.

JLL ranked Shenzhen fourth in the list of the top 20 most dynamic cities around the globe, taking into consideration factors such as speed of innovation, creation of cutting-edge businesses along with new building construction.

Beijing was ranked third and Shanghai was ranked fifth. Guangzhou didn't make it into the top 20.

Popular innovation and entrepreneurship have become hot words in China since Premier Li Keqiang called them the "twin engines" of the country's economic growth in the 2015 government work report in March.

Entrepreneurial youngsters from around the country are flocking into Shenzhen, especially Nanshan district, which is the birthplace of Huawei, Tencent and DJI and is regarded as China's Silicon Valley.

There are those who dream of becoming the next high-tech giant, and those attracted by the city's energy, like Liang Zijin.

Liang, 28, quit his job in Guangzhou at a foreign consumer goods company last year and joined a drone designer and manufacturer based in Shenzhen.

"There are more tempting job opportunities in Shenzhen than in Guangzhou. Shenzhen has many great emerging companies in promising industries such as high-tech, Internet and finance, while the companies in Guangzhou are mainly in traditional industries," Liang said.

"Shenzhen attracts many adventurous, hardworking young dream chasers from around the country. The working environment here is better than the one I had in Guangzhou. It is straightforward and promotions are not restricted by seniority," he said.

"I left Guangzhou because I didn't want a foreseeable future without any surprises. In Shenzhen, I can feel youth, energy and the spirit of adventure."