Which is the best skimmer?

[Coderad]

The footprint is 7 1/2" by 7 1/2", but the is a half wall at 4 1/2" I don't know if I have to keep that or not. But in my "footprint" I have my sump intake pump in there too and it is 4" x 4". I was looking at skimmer at wai's that I could set the actual skimmer be side the sump and just plumb the pump and return into the sump.