I don't know too much about brands other than Hobie but if I was to buy 3 more kayaks and they were to be for different uses it would go something like this:
Stealth fibreglass of some description, mainly for just paddling for the sake of it...with one lure out the back.
Hobie Adventure Island for the obvious reason of using sail-power to cover greater distances.
A small sik like a Finn Gizmo that I can carry easily and knock around a bit in out of the way freshwater spots (if I'm thinking of the right kayak)
Stealth Evo or ProFisha - would swap now if I wasn't physically unable to paddle long distances without pain.
A small yak for creeks just in case I got the urge when winds are too strong or seas are too big.
best yak i ever had, and ive owned AI's, stealths, kingfishers, etc.....
a tandem viking tempo with a 3.5hp tohatsu on the back. best moreton bay rig ive ever seen. paddle out or into shallows, and travel miles inside straddie, the pin, and the bay. i used to put 3 kids in and go cockle gathering, crabbing, exploring etc. awesome craft.