In a 5-car comparison in the July 2016 Car and Driver magazine, a Honda Civic Ex was ranked second behind a Mazda 3 i GT. The Honda Civic topped the Chassis category (including performance, steering feel, brake feel, handling and ride scores), but trailed the Mazda 3 in the Vehicle, Powertrain and Fun to Drive categories.
The Honda was rated a slightly better value. The price as tested for the Mazda was about $1500 more than the Civic.
Car and Driver stated: "We could imagine the Honda earning the highest fun to drive score and reshuffling the order with the standard six-speed manual." The reviewers commented a good CVT is still a CVT and were not fans of this transmission. The Mazda has a six speed automatic transmission.
My two daughters each have a Mazda 3 s GT hatchback (with the larger 2.5 l engine) and love it. I recommend you compare the Civic and Mazda 3 during your test drives.