Like choosing fabric for diapers and liners, fabric for wraps is about balancing the different properties. In general however they fabrics used tend to be a much closer pick making it a bit more about personal preference.
This is probably one of the most popular choices. It is waterproof. So as long as you change the diaper and have the wrap properly placed over the edges of the diapers you will not have a leak. This is why its popular and I really like them. Is there a downside? Yes, bit it's more about preference. It is in no way a natural fabric. It needs to be laundered seperate as it shouldn't go on the hottest laundry settings. And it's not very breathable. That's why I like to opt for no cover at times, particularly in the summer.
Its all natural and designed by nature to keep you dry. Its antimicrobrial too. If you've ever been in the rain in a wool sweater you have a good clear picture of how it works as a diaper cover. And its the original diaper cover material. Also it's super breathable and is warm in winter yet cool in summer. However it's not so great under a pair of pants, tights, sleeper or leggings. That's when you get leaks. Kinda like a compression leak. So as a wrap it has a major downside. Now for a night time wrap under a nightgown or on its own without PJ's or sleepers it's great. So how do people use it? People who are aware of this use Longies and Shorties. These are long pants and shorts made of wool and used to function as a diaper wrap / clothing. You can also get underwear or wrap style for summer days. Wool does require some special care. First you can't wash in hot water (and your diapers and liners should be washed in hot so these go seperately). And (at least) once a month you must add in lanolin (natures waterproofing) .
Fleece and Minky
Fleece and minky are water repellent. It works as a diaper wrap. However like wool it doesn't work as well under clothes (although better then wool). Fleece and Minky are warmer then wool or PUL. It is more breathable then PUL but less so then wool. It can get ammonia build up and require stripping. Using as a wrap only means that ammonia on the fleece or minky wont cause diaper rash, but will acquire a smell that will need stripping. Boiling your laundry at each use (as a washing meathod) will prevent this.
Kushies has the only taffeta wrap I have seen. It is waterproof and completely man-made. It absolutely works. I got my first one with baby #5. It is thinner then all the other wrap materials and you will find way less bulk with this wrap. Like wool it is breathable. Oddly I completely forgot about this wrap till Mom asked me if I wanted the taffeta ones again. Downfall: (other then being synthetic as mentioned) I only know of the one by Kushies and despite the size claim it stops fitting just before 20lbs so you have to switch from infant to toddler wrap a little early. Which is totally doable.
So wondering what I will use? I plan to have some taffeta wraps for daytime (thanks mom for the reminder lol) I am torn between a fleece or wool night wrap. Ultimately I think the downfall of wool over fleece as a night wrap comes down to laundry. And for me fleece will be the easier of the two. For some wool will be seen as easier. I invision making a fleece wrap that will go in a taffeta (over the prefold) as an extra night time layer instead of extra liners. And then sometimes I wonder about wool....I like natural, I've always wanted to go this route. . Fleece.seems easier...but synthetic ....we will see what I end up doing. So although I said I wont use fleece in a diaper, I am heavily considering it as a night time layer worn between prefold and taffeta wrap.
PUL WRAP with double gusset leg