Re: best for a 4 month old who HATES being worn
The ring sling is nice because it doesn't have straps and a "body" that might get in the baby's way. I have a mei tai and a ring sling and my 5 month old baby is much comfier in ring sling because it just is like a pouch for her rather than covering most of her up, up to her neck with just her head sticking out. I can pull the top rail to just under her armpits so she can move her arms, hold a toy, etc.
That said, she also loves being high on my back in the mei tai...she can see everything and I think she loves that at her age, even though she doesn't have much movement for her arms, etc.
loving being a stay at home wife to DH (married 4/11/09) and mommy to DD1 (10/4/10) and little DD2 (5/30/12)