Several outlets have tested and compared single-serve coffee makers, including those from Nespresso and Keurig, to determine which ones are best for small spaces. The tests involved multiple machines from various brands, with some outlets focusing on specific brands like Keurig or Nespresso. The results appear to vary, with some outlets recommending certain Keurig models and others suggesting that the best single-serve coffee maker may not be a Keurig.