An essential for kayaking or canoeing is a life jacket or Personal Flotation Device (PFD).  This is necessary for the safety of the paddler in the event that they were to fall out of the boat, regardless of what kind of water they are in. 

In general for Kayaking a Type II or Type III PFD is recommended.  These are both full jackets however a Type II will provide more buoyancy.  Thus, if you plan on going in rapids or fast moving water a Type II would probably be best.  All of the life jackets listed on this sight are designed for Kayaking or canoeing however and therefore are all a great choice.

Pick one that is your correct size and that you think will fit you comfortably.  Check the options for adjusting it and look at the different straps and clips that have to be done.  Good luck choosing a safe and comfortable life jacket!