I am a big fan of Waterpik. There is good research that they are as effective as string floss or even more effective than string floss. And some people just hate flossing and need an alternative. In my practice, I've personally seen countless patients turn their home care around when they introduce water flossing. I think part of the reason is that it's easier to use correctly than string floss. It's also able to get to challenging areas, like underneath bridges, around implants, and in deep pockets (teeth that have had a history of gum disease can have these).
So which one is right for you?
First, make sure it says Waterpik on it. Somtimes folks use the term "Waterpik" to mean any flosser, like how people might say "Kleenex" when they mean facial tissue. There are a few Water flossers out there but Waterpik is the one I recommend. It has the longest track record of research and the functional elements that effectively clean between teeth and around your gums.
Okay, now let's pick a Waterpik. They have a lot of models available and they're terrific, but I'll try to help narrow down your choices with the three models I recommend the most.
(1) Sonic-Fusion is a Waterpik water flosser and a motorized toothbrush, all in one. If you have normal oral hygiene needs, this is the one I recommend.
(2) Aquarius Professional is my recommended Waterpik for patients with challenging areas. If you have crowns, bridges, partial dentures, implants, and orthodontic appliances then this is the one for you. It comes with different tips that will help you get to your hard to reach areas.
(3) Cordless Advanced will give you a clean like the Aquarius Professional, but it can be held in the palm of your hand. If your a traveler or if you have very limited counter space in your bathroom, this will work nicely for you.