I just finished TROTAR after 3 sitting. After watching almost all of Zhao Lusi's period rom-coms (Cinderella Chef, Oh My Emperor, Prodigy Healer, Love Better than Immortality, and TROTAR), I must say that what makes this drama so special is the great script. We must give credit where it is due - writer 南镇 / Nan Zhen (who also wrote the script for another nice time-traveling rom-com Unexpected 2018) really has a knack for writing stories that don't have repetitive plot devices and competent FL & ML. If I were to rate Zhao Lusi's drama based on Female Lead likability, Male Lead likability, Chemistry, and Script:

Zhao Lusi's Female Lead competence and overall likability:
Oh My Emperor (Fei fei) > TROTAR (QianQian) > Love Better than Immortality (Chun Hua) > Prodigy Healer (Yun Shang) > Cinderella Chef (Yiyi)
** Fei fei is the most purpose driven heroine (saving a whole world not only a city) while Yiyi is the most useless, sad courtesan/entertainer

Male Lead competence and overall charisma:
Love Better than Immortality (Qiu Yue Gege) > TROTAR (Han Shuo) > Oh My Emperor (Tang yi) > Prodigy Healer (Xing Chen) > Cinderella Chef (Chun Yu)
***Qiu Yue is the most enigmatic male lead of any of Zhao Lusi's period character. They tried to create a connection with Chun Yu but it was so bland

Chemistry on and off screen:
Love Better than Immortality (Li Hongyi) > TROTAR (Ryan Ding)/ Prodigy Healer (Li Hongyi) > Oh My Emperor(Jason Koo) > Cinderella Chef (Bie Thassapak Hsu)

Script - how the story evolved, how the characters were written:
1. TROTAR (Nan Zhen)
2. Oh My Emperor (Yu Hai Xia/Yin Hang)
3. Love Better than Immortality (Shu Ke)
4.5. Prodigy Healer (Fang Mo Qi/ Yu Ying Nan/Zhang Jie /Xue Hui)
4.5. Cinderella Chef (Lin Wei Rui/Yang Zhi Li/Yu Ge/Liu Yuan Yu/Qiu Jun Jie) - ***Zhao Lusi was a supporting character here
***TROTAR story was the least draggy while Prodigy healer has the fewest romantic scenes between FL and ML and the most irritating 2nd FL.