If I were you,
I would have gone for City If fuel economy was important for me, because IDSI is known for fuel-efficiency .
If boot space and fuel economy was not a problem for me then I would have surely gone for Swift. Though Swift has decent boot space If C.N.G is not installed, and If Swift is driven calmly then It can give good economy as well.
I will never suggest you to go for Civic since It would be almost 10yrs old and my mind can never accept this.
I maybe wrong but you're heart is saying to go for Civic but deep inside you're reluctant to go for it.
Remember Civic that model has a very very bad economy. You'll regret your decision afterwards.
Secondly The older the car get's the maintenance and care required to keep it running increases.
That's all I wanted to say, baki It's your money and you have the right to decide!