People tend to hold onto Civics for a long time... whatever the generation. Civic owners tend to be "loyalista"...
Many people selling Mazda3s? Well, there just isn't the same amount of brand loyalty... and a lot of people are selling them off to get the new Civic (gotta go with what's fashionable...

).
Resale values, from what I've seen, are comparable. But if you're buying secondhand and are asking what the resale value of your car will be after another five years, it's likely the Civic will have a better value... though I don't know how much better, since the 7th Gen isn't as popular as the 6th gen or the 8th gen.
But you don't really buy a secondhand car and sell it thirdhand expecting a profit. You're still going to lose from 200,000 to 250,000 pesos in resale by that time.