As a frequent traveler on the Lucknow Kanpur route and local domicile of Unnao, I experienced that some trains act as a lifeline for this route:
1- Chitrakoot Express:
It is the favorite train for the students who study in Lucknow University or any other institution. Due to its timing, this train is the up-down option for mostly all students. It reaches Lucknow by 9AM and departs at 5:30 pm, making it the most used train by the students.
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Lucknow Jhansi Intercity:
This train is most important for its route after Kanpur because it is one of the fastest trains between Kanpur and Jhansi and also its connectivity with Lucknow is really beneficial for passengers of this route. This train is also used by many students as it departs at 4:40PM from Lucknow.
3- Lucknow Kasganj Passenger:
This train has its most patronage after Kanpur Anwarganj but it is also a most preferred option for students of the Lucknow - Kanpur route because it is the only train in the morning that provides direct connectivity with Rawatpur (Kakadeo).
4- Gomti Express:
This is one of those trains which have the purpose to serve the passengers of the stations in between the route. It has most patronage from Etawah, Kanpur, Aligarh, and Tundla. It also acts as a returning train for several passengers going towards Lucknow.
5- MEMU services:
Although MEMUs are really very preferred options of every traveler, due to their low priority and frequent overtakes, these trains have not reached their potential after COVID.

Honorable mention- Varuna Express:
No one can deny the fact that this train was the legendary train of its time. The only daily end-to-end train between Kanpur and Varanasi, it also acted as a mid-day travel option for passengers from Lucknow, Unnao, and Kanpur.