Maax spas until recently were the Coleman Spas. There are the same tubs, just under the Maax name. I been selling them and they are really nice spas, In My opinion they give you the most for the money. The Company who owns Maax is strong and they really take care of customers.
The warranties of spas are indeed included in the price. Most have 5 year plumbing and equipment, 3 year on lights and 1 year on any radio features. Wet test spas and any you pick that are made from a name spa manufacture as you have listed, you will fine.