To be honest.
I have used both Generations city at same time with swift. (City 2006, swift 2015) then (city 2009. Swift 2015).
Lets talk about the 2009-2010 city as you asked.
I will give just 1% advantage is all aspect to swift.
Acceleration , comfort , drive.
Ac of both cars are almost same, if maintained well.
In pick, swift is very good. (Again if maintained well).
In simple words, its about your priority, if you want a bigger car, city al the way.
Newer car, swift os the option.
There are 2 things matter i guess
Mileage and trunk
City got both the points.
If you are okay with the mileage issue go for swift.
Provided if you got a maintained car.
Just saying, i sold mine manual city 2009 , only 94k driven , well maintained, total genuine except 1 bumper 10months back but higher then the price you think you can get an auto.
City suspentions are stiff/hard , my persnal experience.
If you maintain swift good, it will give you good mileage.