TS, I have the same thought - elantra, cerato, and city.

Started my research since Jan '18. And finally bought a car. 

Summary
As mentioned by other poster, Elantra and Cerato falls under C-Segment while City is B-Segment.
I will break it down as followings:

Fuel Consumption: There is no doubt Honda City wins in this compartment. C-Segment cars are definitely heavier and bigger in size. You can compare the FC between the cars at fuelly and also our very own FnF ‘s FC thread : https://forum.lowyat.net/index.php?showtopic=314774

Handling: Cerato and Elantra have fishtail issue (source: car clubs thread in LYN). City is so-so. Nothing to shout about. But if you are driving in Klang Valley and traffic jams everyday, you don’t get to experience ‘good handling’ anyway haha.

Maintenance: You can compare how much the service will costs. Honda’s you can check from their website. Kia’s I gotten from Cerato FB group. Probably can be also found on Kia’s website.

Comfort: I have test drove all 3 cars. Cerato and Elantra definitely feels much more premium and more stable when driving at high speed. City is pretty decent.

Common problems:
Cerato : Spring clock & flex coupling – very common issues
’14 City : Door-side rubber’s hole can get blocked.
In the end, I bought ’14 City V. Costs much higher than the other 2 cars but FC matters to me a lot.

I suggest TS to join those FB groups for the specific cars. I have learned a lot from actual car owners. Look at what their common problems, sharing car service receipts , etc. 

Good luck with your car.