Being an owner of honda city (6th gen petrol) here in india and having been driven my friend' yaris( also petrol ) quite a lot of times , here are my two cents:
Exterior :
Looks might be subjective but I find both car's design quite modern and appealing.
City with its large chrome grill and nice alloys seems quite nice to me. Yaris is also not far behind and I like the headlights and tail lamp's design and overall shape in general.
Interior:
Here too I find both the cars performing well . Although city with a better plastic quality,sunroof, touch screen auto climate control and a responsive touch screen audio unit gets an upper hand here.
Safety :
Yaris hands down, yaris comes in India with 7 airbags and both front and rear disc brakes . When i bought honda city in 2018, even the top model came with only 2 airbags.
Fuel Economy:
In city traffic : Yaris: 10-11 km/l, City 11-12 km/l
On highways both cars give almost around 17-18 km/l
Engine :
Yaris's engine feels superb in city traffic. You put your foot down in any gear and you always have this low end power available to you . However when it comes to highway drives its the city's engine that'll put a smile on your face. Yaris's engine is not as refind as honda city's.
City on the other hand with more power and torque performs very well during highway drives. The engine is rev happy and you get that nice push in the seat feeling when you rev it till 5k rpm. I'm talking about the 1.5 L petrol in both cases.
Suspension, handling and comfort:
Yaris suspension is tuned on a softer side meaning that it absorbs potholes and city bumps well at low speeds.
City with a hard suspension performs not so well in city but out on a highway there's no match. It feels planted and overall with a more responsive and sharp steering wheel , and a better dynamics you'll enjoy this car a lot on highways.
Verdict :
Go for yaris if you love being driven around and your drive is mostly in city traffic.
If you are a driving enthusiast and love high speed driving and cornering on highways go with city eyes closed .
Regards
