Bubble king is probably the best however they are very costly. How big is your tank? What is your bioload? On my nanocube 28 g I have used a tunze 9002, aquamaxx hob-1, and sapphire aquatics nc28. On my old 120g I used a reef octopus nwb200. On my current 30g shallow cube I have used reef octopus bh50, and just changed it up to an eshopps s120.
Bubble King or Deltec, but as empire points out, its all down to budget, but usually worth every penny you invest in them. Every Skimmer maker will have a unit designed to different volume tanks at standard and high stocking levels. I personally like to go 1 size up from recommended (building in some future proofing).