I've run both, and I've liked both for different reasons.
What drove me nuts was the AC110 had a hum to it. I had two of them, they both did it. Now, I did have the tanks on a metal stand - but on carpeted floor. I also have a n issue where certain frequencies bother me and nobody else in the house notices it. So, keep that in mind. I liked the filter though, it doesn't have a flow of water that sprays so the glass lid won't cloud up.
The Emperor 400 has had it's own issues for me. I have had these filter forever, and the old ones with the water flow pull in the back have been great. I have two of them right now that I searched for because they were old. The new ones don't have a flow pull in the back anymore, and they seem noisier too. It may be my hearing again, but the old ones were much more quiet from what I hear coming from them.
As for media options. I have modified my 400's to a large ceramic block bottom and a foam block on top, it runs more like the AC110 now. I also used the foam top to hold pothos in place, they root into the foam and to clean it all I need to do is lift the plants and the foam and wash it out in a bucket. The roots handle the washing just fine.