Design on all three are similar, customer service w/ Reef Octopus (Coralvue) & Avast are both top notch (no experience w/ SWC), and the only real difference is air draw. If you look in the DIY forums of RC the one thing everyone tries to modify on their stock skimmers is the impeller to increase the air draw.

I have an ATB Mikro skimmer that used to be powered by an Eheim 1250. Air draw on that was around 350lph w/ a meshwheel and performance was okay to say the least. I upgraded the pump 2 weeks ago to a PSK-600 and I can definitely say that my skimmer went from okay to a truely great skimmer. I was planning on buying a new skimmer for my 150 gallon tank that I'm building, but I think I'm going to use the Mikro on it til the bioload outgrows it.