The boxes that is. Even more swell if you barely can fit in them. He enjoys bags too, but boxes seems to be what he loves the most. If you just let one lie on the floor, he will claim it his and sit in it whenever he finds himself out of other things to do (sleep or hassle our other cat, kapris). Unless you make an effort to make the box cosy with a blanket or something, then it's all of a sudden utterly uninteresting to him.
Here he is, in all his glory!