I have always bought the 100% cotton pj's for LO's. I know the polyester ones are made to be non-flammable, and can fit looser, but they just have such a 'waxy' feel to them, to me. And I worry about whether they are as breatheable, and if LO's would sweat in them. I know whenever I've bought pj's or nightgowns made of polyester, I just am not comfortable in them.
Do you buy them for your LO's and do they seem to do ok with them?

Re: Do you buy the polyester material pj's for LO?
It depends on the kind. Some of the cheaper ones feel gross to me, so no. But the Carter's ones feel like light cotton to me -- I actually prefer those in the summer because they are soft and much lighter/thinner. Here is an example:
https://www.carters.com/carters/3-Piece-Print-Jersey-Pj%27s/V_372-316,default,pd.html?cgid=carters-kid-girl-pajamas
Otherwise I buy snug-fitting cotton ones.
I try not too because they feel so gross to me, they pill like crazy, and they trap odors because they are synthetic and don't breathe. I prefer cotton jams although they tend to be more expensive.
Although these days I don't have a ton of choice because DS1 is totally obsessed with picking out his own clothes so if it has a dragon or dinosaur he doesn't care what the fabric is!
I don't mind the polyester flannel jams from Lanz though. It seems to be a better quality
The bold is the reason I tend to stay away from them. That said, we do own quite a few. They are cheap and readily available and if I haven't had time to get cotton gymmies from Gymboree or HA from Costco then in the summer DD wears the three piece Carters ones from Target (short sleeve shirt, shorts, and coordinating pants).
Anna is so big for her age that even a size up, her arms and thighs don't fit into the snug fitting cotton ones. By the time I'd move up enough sizes for her to squeeze into them, they'd be loose fitting and defeat the purpose. So we used to buy the polyester footie pajamas for her... usually carter's, and I had no complaints with how they feel or breathe.
Now she is mostly in cotton 2 piece pajamas, as those tend to fit her better.
Because we're fancy like that.