Never used the EP fibers but it kind of looks like craft fur, and never tried the Polar-Air but looking at it on-line it looks like a hank of wool.
The SLF dubbing is excellent!!! I have a bunch of colors in it, when using it to tie small jigs don't over-do a little goes a long way. The old saying on dubbing is take what you think you'll need, take half of that and then half of that. On jigs follow the first two parts of it.
With these cheap home made tools you can make dubbing look really buggy looking, use both sides of the Velcro - the stickly side will make a buggy look the smooth will help blend fibers together.