Top 10 Greatest Chinese Emperors

He was the guy who unified China after hundreds of years and centralised money and units of measurement, and was the first person to use the 'huangdi', or 'emperor' title. Note: Qin Shi Huang is a title - he never had a posthumous name, so 'Qin Shi Huang' translates to 'First Emperor of Qin'. His real name was 'Ying Zheng'. He's also on my 'cruelest chinese emperors' list for killing his people in building the Great Wall and Terracotta Army.
I head he was the first emperor of China. This guy was a great leader.
A good but overrated emperor. He was able to beat the northern nomadic tribes - and not being able to rain them in had disastrous consequences - the later Jin dynasty was unable to control them, leading to a 300 year period of disunity. However, he had to publicly apologise for his actions, killed his eldest son's family over witchcraft rumours, and became heavily invested with magicians.
Note: Emperor Wu is a posthumous name meaning 'martial'. His personal name was Liu Che.
The guy who reunified China after the aforementioned 300 year period of disunity. Without him, the concept of a unified China may have been something that people forgot and might have become a thing of the past. He was also very loyal to his wife, Dugu Qieluo, and never had a child with any other woman (which was an impressive feat for a Chinese emperor; for example, Emperor Taizong of Tang loved his wife Empress Zhangsun deeply - it didn't stop him from doing his emperor's duty with other women in bed)
Again, 'Emperor when' is a posthumous title meaning 'civil'. His personal name was Yang Jian.
He encouraged his officials to speak out and criticise his actions, hating yes-men (it might not sound that different to a modern viewpoint, where political leaders are expected to take criticism - but 7th century emperors weren't). Like Emperor Wu of Han, he was able to subdue his northern neighbours, and created a prosperous empire, where ethnic minorities were treated well, his reign being a well-known golden age, and required study material for future crown princes.
Again, 'Taizong' is a temple name meaning 'great ancestor'. His personal name was Li Shimin. He took the throne in a fratricidal coup, but that's a matter for my own list 'Cruelest Chinese Emperors'.

She was able to select talented officials, and was a very good administrator. She might have been cruel to her family, but continued Emperor Taizong and Gaozong's golden age into her reign, and selected officials based on merit rather than background. She even made a woman, Shangguan Wan'er, her secretary, and she enjoyed lots of power. She was considered such a role model to ambitious imperial women after her death that her daughter-in-law Empress Wei, daughter Princess Taiping, and granddaughter Princess Anle tried to imitate her.
Her birth name is unknown - Zetian was part of her title. She changed her name to 'Zhao' upon becoming the emperor (a gender-neutral title).