There is no doubt City is much better than cultus, but cultus being a car who's spares are always available at a much better price than City's spares.. I would have suggested you to buy cultus if it was a used car as compared to city.
Broh selling a car is easy, but finding a car 'good' car is almost impossible.
Those with good cars are not selling it. Those selling a car generally are the people who are fed up of their car.
If you have experience of buying a used car you should know. People sell completely accidented cars and tell that its bumper to bumper genuine
If I were you, I would not buy a used city while I can afford a new cultus.
A new car is much much better than a used one. You will not have the worry of taking it to the mechanic for atleast 3 or 4 years if you drive it carefully. Also the cultus with Efi, Power steering etc (VXRi) is a very nice car to keep.
Then it has a great resale and also very cheap spares. Suzuki's spares are not comparable with anyone that I'm sure you already know.
So if you're too sure about a City that its a clean one (meaning you're buying it from a relative or friend who bought a new one) then definitely go for city.
But if you're going to go and find it in bargain centers and melaz then I won't suggest you that.
Zero Meter Black VXRi Cultus would be a very good choice in my opionin as compared to a car which could be a risk. Buying a City will put you in a risk while you could afford a brand new car.