I've just liked them for as long as I can remember.
When I was 5 it took me a long time to get to sleep so I would lie in bed and fantasize about wearing them, or being forced to. I didn't know why I liked them but I recognised even at that age that it felt naughty. So I never told anyone
Now I mainly just like how they feel, especially the bulkiness between my legs when I wet. It's entirely a sexual feeling though, and I'm not sure that I believe the majority of people claiming to like diapers for only non-sexual reasons. I guess it's just easier to explain to people?
I also get off on the humiliation aspect a little, I'm not sure if it's related but when I was 5 or 6 I was at a campground and had to wear pull ups at night (I wouldn't usually at home, even though I wet the bed every night). After putting one on and getting into my PJs I had to go down to the other end of the campground with my dad to brush my teeth. It wasn't that late, only just getting dark so there were still plenty of people outside. It doesn't make much sense to me now but at the time I was absolutely certain that they were all looking at me and that they could all somehow see what I was wearing, no matter how much I tried to tell myself otherwise. It's probably the most embarrassed I've ever felt. I guess at that age these sorts of things leave an impression on the mind.
On the last morning before going home I decided to just leave my wet one on when I got dressed