For book/ebook authors, publishers, & self-publishers
First of all, the three you mention don't have good reps. I know authors who have had bad experiences with them, also Outskirts. In particular, you should avoid their marketing packages like the plague.
I've had good luck with Infinity when I was still doing POD. Now that I'm just doing ebooks, I use an OEM formatter and cover artist. That's what works best for me...complete control!