Choosing the right bathtub means you'll need to consider several different issues. Some of them you'll have control over, like how plan to use the tub, while others are more or less controlled by your situation -- like the constraints of an existing bathroom for example.
The spectrum of choices runs not only from the purely aesthetic but to the type of bathtub you want as well. Choices include everything from the basic alcove tub to sophisticated air tubs or a sleek, modern slipper tub.
Technology also factors in to the choices you have available to you. Not only have bathtubs evolved to include whirlpool jets but now you can incorporate light and sound too. The entrepreneurial spirit has also fostered unique creations like wooden tubs, though there are considerations to think about closely with these kinds of tubs.
The bottom line is this -- choosing a bathtub requires some up-front knowledge of your situation, how you'll use the tub and what's available. Getting this foundation will help you on the path to making a wise and hopefully, "cleansing" choice.