I'd say more effective.
"Insects have a more efficient respiratory system than humans. "
But at the same time insects don't have any lungs they breathe through the help of trachea/tubes/and or holes along their abdomen area.
You need to think about how small, compared to us humans, and insect is. They can take in a lot more oxygen than we can (for their size)
If we were to be able to shrink until we're the same size as an insect, they would be the ones taking in way more oxygen because of the way their system is constructed.