Speaking from a tourist point of view, Perranporth is lovely, I think its a spectuacular little town, but it is that, a little town. If you want to be able to see a few things and do something, newquey is the place, bit supermarket, lots of shops, lots of surfers (Oz link) and a good night life.
If it were me flying in as someone who hadn't seen either, id pick Mawgan, and if you want to see Perranport while your there, its not far at all!
Hope it helps, . .Rusty.