We bought a Wilderness Systems Tarpon 130 Kayak. It’s a 2+1,(our three year old can just about go in the +1, but you couldn’t go much bigger.) It’s great in the sea, very stable and seems to go quickly.
It’s not massively easy to get on the roof of a car, even with two people, and I don’t think a single person could do it without risking damage. Once on there, you can’t fully open the boot. It weighs c.30kg, so needs two adults to portage.
Storage is not trivial either (I believe you can deform the hull if you don’t store it correctly).
If I’m honest, I wish I’d bought a single seater, and hired two seaters when needed. It’s great when in the water though 🙂