I had a Somatic S60 6" needlewheel from Vertex (BulkReefSupply, $199). Was pretty darn big (6" diameter), but Sicce pump and worked very well. I ended up replacing it with a refugium, so I don't use mine anymore. I would certainly recommend it if you want a high quality skimmer with a reliable pump that works well (and you don't mind it taking up most of the skimmer compartment).
I'm curious what issues you're having with your Aquamaxx, as I've been debating getting a small skimmer that would fit in the sump for emergencies without my having to remove the refugium, but I'd only be able to fit a small skimmer like a K2-50 or Aquamaxx WS-1 (hence my interest).