Rack Systems: What's your favorite?

I have experience with different manufacturers over the last two decades and my personal favorites are Animal Plastics, Vision Products and Freedom Breeder.
Each are different, but they also have their own advantages/disadvantages at their own price point. I would recommend making a list of what your requirements are, because it is different for each individual depending on their facility and the species they are keeping. Examples include: durability, weight, mobility, pricing, ability to hold humidity, size of tubs, shipping costs, accessibility of new tubs, heating source, accessibility of replacing heat tape/cable, etc. Look closely at your top requirements, then decide which company provides the best value.