Anything that has a high return. Kiosks in malls are very expensive and you have to meet certain criteria to even get a spot. You also need to have a very good plan and be able to prove you can add to the malls desired image and keep a profitable business. Realize that rent increases when the holiday season arrives. This is why most kiosks you will see are either cell phone retailers, or specialty items with good margins.
I am curious as to why you are asking the question. Is it because you just want to see what might be good to sell at a kiosk? Or. Is there some sort of special event that is being planned or season that is coming up where you will have opportunity to operate a shop out of a kiosk at a mall? Your best answers you receive here might depend on your answers to those two questions. Then again, maybe not. I'm just curious...
I know that around where I live, there are more kiosks at the malls only at certain times of the year and during special events in the community.