I love my pikkolo, but I haven't tried the others. It has been great for back carries and it is fine for front carries. It does hip carries okay, too, but I prefer the ring sling for a hip carry. I chose it over the Ergo and Beco because I wanted the option of forward facing front carries - my husband's preferred method.
The disclaimer is that I got it when DS was already 7 months old, able to sit up on his own and over 15 pounds. So I have no experience using it with a small, floppy infant.