i drove a mazda3 low spec too, occasionally i also drove my cousin's civic tc-p

just my 2cents lar

safety wise : both about the same, equipped with 6 airbags, vsc and abs, but mazda 3 feels more planted and stable on high speed

NVH : Got to say civic winds all the way, mazda road noise just too noisy, but 16" on low spec should be acceptable

Value : i would say civic, as its an all rounder car, most probably higher resale value in future too

comfy : Civic is leading in term of passenger comfort and interior space, but for mazda is driver's comfort, go test drive both, mazda driver's position just right on the spot! very comfy yet sport! civic seat also not tat comfortable for long distance driving as the seat is quite flat, your thigh will be actually hanging in the air above the seat. Go try it. Mazda3 stock sound system also way better, the MZD player also much more responsive than civic laggy player.

Quality : Mazda 3 built quality is better in term of fit n finishing as well as material used, more soft touch material found in mazda.

Handling : no nid to compare, mazda way better in handling, but low spec 16" on mazda3 isnt going to be very good but still better than civic, switch to 17" or 18" then u will notice the huge different. Mazda steering feels much more direct, civic steering feels a bit numb to me.

conclusion : if u r always driving this car alone, get mazda3, cheaper and free 3 years maintenance (100% free), if u plan to get it as family car then civci no doubt, the best all rounder and reliable car in this price range.