I was using vermiculite, but had a couple babies get it stuck in their eyes. I'm using perlite in my incubator now and leave the vermiculite for moist hides.
I've always used vermiculite. I've never had any go bad. Though, it can be messy so I've been thinking about switching, but I'm a firm believer in, Don't mess with a good thing/If it ain't broke don't fix it. So I'm hesitant.
Perlite personally. I've only ever used Vermiculite once for a clutch of corn snake eggs. It was too messy IMO and turned everything it touched gold plated(including my female corn though I won't add a picture) so I prefer perlite. It looks neater, smells better(my vermiculite started to smell after about 4 weeks in the incubator and I had to change it) and is just all round better IMHO.