Just like bikes, a 'yak needs to fit. I did a whole lot of research on "properties" of kayaks but without nearly enough understanding, and wound up with one that's too big for me and just uncomfortable and impossible to paddle efficiently.
It's good to acquaint yourself with the concepts of primary and secondary stability, and have a clear idea of what kind of paddling you plan to do. Then do some rentals/test paddling (IME it's a lot easier to find quality rental 'yaks than bikes), but pay attention not only to how the boat feels in the water (as I did), but how you feel in it.
"I felt [the women's Olympic marathon] was as important as women having the right to vote, because talent, strength, and capability cannot be fully realized if there are no personal rights to allow them to be visible or be deemed significant in the first place." - Kathrine Switzer, Marathon Woman