High capacity storage tank and good customer reviews are what made me go with that one. I have the Herpstat set to hold it between 50-55% and it doesn't have a problem keeping it there with our dry AZ desert air. It goes through 0.5-2 gallons a day depending on the season, so part of my daily routine is to fill the tank. It's got a removable canister for easy refills that empties into a larger holding tank.