I've researched online and definitely want a Nespresso (based on ease of use and cost). I can't decide on which model. I don't understand the pricing between the CitiZ, Pixie, and Inissia (unless it involves the amount of plastic vs. metal?) I also can't decide whether to choose one of the above with the Aeroccino or go with the Lattissima, which integrates the milk compartment. Does anyone have any experience/opinion about any of the products? Thank you in advance.