Driven AQUA briefly. 2011 FD3 is my daily drive for 3 years.
1. Fuel Efficiency - Aqua by a long shot. If my friends are correct Aqua does 20-30kmpl even on city traffic while the max Civic hybrid would do is about 24kmpl on highway. It Colombo traffic it would do 10-15kmpl depending on the nature of traffic.
2. Comfort - Civic. It also has the better looking interior.
3. Pickup and Handling - Civic. The Aqua just felt boring for me. The Civic felt better to handle and snappier on the acceleration than the Axio Hybrid actually.
4. Never maintained an Aqua so I can't tell for sure. As for the Civic there is nothing unusual to maintain as long as you service it properly and keep the car running. If you don't run the car often, don't get the Civic hybrid.
And if you are getting a used one, get the IMA battery capacity check done by Stafford motors. Get something with capacity above 40% (max is 75%). If you get one with a dying hybrid battery (mostly caused by not running the car for weeks at a stretch or sitting at a car lot or a ship) it will cost you 2lakhs-5lakhs to replace it.
If you buy a model before 2009, make sure the system software is up to date. Models before 2009 had a problem with the IMA software where it would overuse the electric motor, causing the hybrid batteries to die out quickly. Honda fixed this is in a software update available for all models, and came pre installed on post 2009 builds.
If you buy a car with hybrid battery recently replaced, makes sure the car runs the software that matches the new battery. Most people replace the battery and don't update the software. If it's not up to date, get it updated at a service center.
If possible, just test drive both cars and see for yourself. As usual I see on this thread advice from people who have not driven either one of these cars. Only you will know what you like for sure.