There is no perfect enclosure. Racks are great space savers but have limited heating methods and in cool room (<68ºF) temps can be very hard to maintain correct ambient temps. The solution most use it not to use racks in cool room temps but to heat the room to 80º. tanks with open tops do lose heat and humidity but they also offer economy and the widest range of heating appliances to maintain heat. Plastic enclosures are in between offering a balance of heating options with good looking efficiency. Tanks can also be side turned offering many of the benefits of plastic with the cleanliness of glass the cost is complex hanging fixtures. No type is clearly better each have their own challenges personally I use side turned tanks custom designed enclosures plastic commercial enclosures (slab built and roto moulded) as well as a rack. I have no problems with humidity or heating any of them I have solved issues I encountered with each one. The question isn't which is best but which suits MY needs, the location and my abilities the best. It is personal there is not right answer every set up location and keeper differs.