The problem is, if you ask 10 babywearers "what is the best sling for xyz," you'll probably get 20 different answers!
For newborns, I love:
fleece wraps (depending on season of course)
open-tailed non-padded ring slings (or with light padding in shoulder and/or rails but NOT closed tail/heavily padded ring slings a la NoJo or OTSBH)
Bali Baby Stretch GypsyMama wrap as a PP mentioned
fitted pouches for quick in-outs
and of course tall-bodied MTs for the incomparable ease of getting baby on my back in a high-back carry! (totally doable with a wrap but I like a MT better for this purpose).
See, that's just me and you've got 6 different answers right there!