I SUGGEST you go for a new small car. The latest models from the established manufacturers (including the two you mention, as well as several others) are lighter on fuel, safer, and more comfortable than their predecessors.
Space for front-seat passengers is often equal, and sometimes better than in bigger cars of a few years ago. By buying new you also get the benefit of a factory warranty and service plan (standard or optional) that helps to keep the servicing costs down during the first few years of ownership. With a used car there is always an element of risk and uncertainty.
The only department where a small car cannot compete on equal terms is in luggage capacity (and perhaps rear passenger space).
If you regularly have to carry a lot of bulky luggage, and if there will often be four or more adult passengers in the car, the scales might begin to tip towards a bigger, second-hand model.
Even then I would first go for a test drive in a few of the small cars on your shor-list, to see if the rear seat space and boot capacity are really inadequate for your needs. Make the most of these test drives and be sure to include a few small automatics in your list of candidates.
In city traffic a car with automatic transmission is undeniably more relaxing to drive.
Modern automatics are no longer significantly heavier on fuel than manual transmission models, and they give you the peace of mind of not having to worry about the hammering that the clutch takes in stop-go traffic.
The new car market is a buyer's market at the moment. Use this to maximum advantage when negotiating with dealers about things like extended service plans and optional equipment such as a gearlock, aircon and sound system.