I have the Bubble Magus Curve 5 in my 20L DIY sump. Produces awesome skimmate, very quiet, never had any issues with it thus far (almost a year). Recommended water depth is 9.5" - 11". Footprint is very small and rated up to 140 Gal. Retails at about $209.
If your looking for a cheaper but efficient alternative I have heard rave reviews about the SCA Aquariums 302 (180 Gallons), SCA 303 (150 Gallons). They are in the $170 range. I can't speak too much to these since I have never owned one but from videos and reviews they seem a decent low cost alternative.
Other more experience members please feel free to chime in if I'm slightly off the mark on my two cents.