Salam
Buying a used car is tricky. You have to consider your requirements such as daily driving, family size, fuel affordability, maintenance cost, road conditions of your area or city, etc etc.
I have kept a 7th gen Civic Exi manual for over 16 years and it’s a good car. Solidly built with good handling characteristics and maintenance is not that expensive either. But it has its fair share of problems like power steering pump leaking, low ground clearance, poor throw of headlamps, oil leakages from various seals like the tappet seal or the main seal. You have to change timing belt at regular intervals as well. The suspension is also fragile and it's not built to be driven in rural areas. The braking performance is very good. VTi has ABS while Exi does not have it but still it's very good.
Fuel consumption is 10 -11 km/L with AC in city during summers and around 12-13 in winters (if you change gears before reaching 2000 rpm. On long hauls it's around 14 if you keep it between 110-120 since the rpm stays close to 4000 at these speeds. The automatic version of Exi and Vti would give slightly better average on long routes but abysmal average in city driving. Rear passenger space is adequate and the flat floor is a plus. Rest of the interior is pretty basic. AC performance is good if you service it regularly. Driving position is very good and placement of A pillers does not hinder your view in turns
Finding a maintained used car is not easy. You'll find many with meters reversed or engines swapped. Finding a good seller is even more difficult because most of the ads on pakwheels are by dealers. They have absolutely no idea about the maintenance history of the car. So you will have to test drive many before you find the one that clicks all the boxes for you. So try finding a car that has ownership history.
I have no idea about the swift. The only thing I know is it has a feature that's not in the 7th gen civic which is a clock in the dashboard. But then again the civic has a boot. 
Good luck!
