I can agree on the Kirby-it can eat pet hair like no tomorrow-----BUT the outer bag can STINK from pet debris clean-up.For Kirby users having to clean up after pets the outer bag has to be cleaned or replaced more often than for homes without pets.And-Kirby does now provide carbon granule Filtrete bags for pet owners-this should solve the outer bag odor problem.With all plastic bagless machines like Dyson,Shark,others-their filters will need frequent replacement.The dirt bin will have to be dumpted for sure after each use.Their cyclones absorb pet stench-they will have to be cleaned by a vac shop quite often.Of the two-I would go for Kirby.I don't have pets but see the machines pet owners bring into the vac shop because of pet smells.