So it seems neither is more than efficient than the other when it comes to internal or external.
No one said that?! We recommended an HOB filter for you.
You need a filter that can turn your tank over 5-8 times an hour, it should have separate places for biological and mechanical filtration and should have the ability to hold chemical filtration in the event you need it.
The design of the Emperor 400 does all of that and makes maintenance super easy. Internal filters are challenging at best to maintain.