This may be a somewhat unclear topic title, sorry about that. Anyway, what I was wondering.. which term do you prefer to describe yourself, in terms of feeling like a little kid? (If you're DL only, then this topic doesn't apply to you)
'AB' or 'Adult Baby' has pretty much been the standard throughout the community. If you first stumble onto websites and forums about activities like these, you learn that you may be called a DL (if you only like diapers) or an AB (if you like to feel like a little kid in general). The upsides of the term 'AB' are clear: it's short, sweet and discreet, and has a nice ring to it by placing the contradictory terms 'adult' and 'baby' next to each other. A downside is that it's not always accurate, as most AB's actually prefer to regress to an older age, to the point that they would no longer be called a baby. You could solve this by calling yourself an 'Adult Toddler' or an 'Adult Child', but then you'd just be drawing increasingly unhelpful lines. Also, for a lot of AB's, the age they regress to is not set in stone.
The term 'Ageplayer' groups all of the ages together - if you like to feel like you're a different age than you actually are, then you're an ageplayer. It solves the problems mentioned above, but does create a new set of problems: is everyone who behaves like a child at times an ageplayer? If so, than most of my 'normal' friends are ageplayers as well as soon as they start to play tag or hide-and-seek. Also, are you an ageplayer if you're an adult who wants to be 16 again, or if you want to portray an elderly person? That's clearly a wildly different thing from wanting to wear diapers, suck on a pacifier and watch children's cartoons while holding your plushie.
There's a third term that solves both of the problems mentioned above. If you're a 'Little', it means that you regress to a young age, but it's not specified what age exactly. It can be specified what gender you identify with when you're regressed, as in 'Little Boy/LB' and 'Little Girl/LG'. Some people even call themselves a 'Lifestyle Little' to illustrate that being little is not just a hobby or a fetish, but a way to live their lifes. This term comes with it's own problems, though - mostly linguistic issues. If you say that you're a 'little boy' or 'little girl', who says that you don't just mean you're physically small? Also, saying to someone else "I'm a little" might lead to the response "I'm a little.. what? Tired? Hungry?"
Finally, 'Infantilist' is more of a technical/official term, but I've heard people use it to describe themselves as well. If you're into (paraphilic) infantilism, you're an infantilist. Clear, but it may sound a bit too medical.
If there are any other preferred words for 'people like us' that I forgot, please feel free to mention them.
As for myself, I generally just use "AB", although a case could be made for any of the other options as well.