I have been sea kayaking for a couple years, and over that time I've developed some opinions about what I would like to have in a new one. My current kayak is a Wilderness Systems Cape Horn 15 that I am at least the third owner of. It is a good boat, but doesn't quite fit my ideal. The one I had previously, a Wilderness Systems Tempest 170 was much closer, and sets the standard by which I'll judge all.
All sea kayaks are good boats. You have to find one built in a style you like, feels good in the conditions you will be paddling in, and fits you.
The number one priority is an adjustable skeg. The Cape Horn has a rudder, and I have yet to put it in the water. A skeg works as well with fewer parts and a cleaner looking boat. The only disadvantage is storage room taken up by the trunk in the aft compartment.
It should have recessed deck fittings, 3 bulkheads, day hatch and good size bow and stern hatches, perimeter deck lines, lots of bungie cords, at least 16' long, under 24" wide, good initial stability, great secondary stability, and a good physical fit.
Besides another Tempest 170, my list of potential boats includes:
Current Designs Sirocco
P&H Capella 166 RM
Necky Chatham 16