When shopping for a hot tub, jets are one of the most important features to examine. Sure, you want a hot tub with a good-looking shell and cabinet, but looks only get you so far. When you need a good massage at the end of the day, it's the jets that will make it or break it for you.
Here is a summary of the tips offered by the helpful book What Color Is Your Swimming Pool?:
Although the newest models of luxury hot tubs often offer numerous jets (30, 40, or even more), more isn't necessarily better. Fewer jets may suffice if they are well-placed. When shopping for a hot tub, hop in the various models on the showroom floor (even better if you brought your swimming suit and they have some filled, fully functioning hot tubs to try) and pay attention to
where the jets will hit your muscles when you are relaxing in the seats. A really good jet that gets you in just the right spot can be worth a lot more than numerous jets that hit the wrong places. You may feel weird wearing your swimming suit and climbing into a hot tub in the middle of the dealer's showroom, but this is the best way to ensure you get a model that suits you. Since most hot tub jets are controlled by an "aerator" or air blower (the purpose of which is to control the power of the air coming through the jets), you won't really get a feel for how powerful the jets are until you try them in the water. So, when you're testing that hot tub out in the dealer showroom, play with all the controls, and try the jets at various intensities.
Specialty Hot Tub Jets
Many of today's hot tubs come with jets that are trademarked by certain manufacturers because of their uniqueness. Some examples are oscillating or rotating jets, handheld jets, cluster jets,
neck jets, and carpel tunnel jets that focus on the wrists and hands. Whether or not you need or desire these fancy features is up to you, but definitely try them out in the water before deciding as they often come at a premium price.
Source: What Color Is Your Swimming Pool?