I use sleepsuits and Pjs on my DD (she's just 6 months). At first I preferred sleep suits, but now I find PJs easier to put on her as since she started sitting up she wants to be dressed sitting up too
I also think she likes rubbing her feet together and feeling skin on skin in bed, and they seem to last longer over her big nappies as I can just pull the trousers down a bit if needs be. Sleep suits seem to be too short in the body and too long in the leg at the moment.
I'm going to stop buying sleepsuits from now on (she's currently wearing 9-12 mth size) and just go with PJs.