I only use Fleece as the main material in retaining liquid and not PUL :)
1. It's more breathable.
2. Dries Faster
3. Doesn't stink up during use and after wash
4. No washing rules about it. Toss in with diaper laundry, into dryer, and back onto baby! Simple! This cover washes well and has only gotten SOFTER with multiple washes!!! It washes up easily, dries fast, and is super comfy for baby!
5. It is also super easy to use and care for fleece
The only set back about fleece covers is that in general it would be that depending on how heavy of a wetter your child is and/or how frequent you change them, you may only get one use out of your cover before it needs washed.
You can click HERE for a very good review on Fleece Covers for better understanding :)