I have only tried a moby wrap with #2 and I never got the hang of it. I'm expecting #3 and I was thinking either ergo or beco. What's the best and why? I have got to baby wear this time. #1 and #2 never let me put them down when they were little, so I'm assuming #3 won't either.
"Best" is completely subjective, like if Nike or Reebok are better sneakers. The answer is that it depends on your foot. Do you have a local Babywearing International (or other babywearing group) chapter? That is a great way to try on lots of options. That said, to answer your question: I prefer the Beco because I am under 5'2 and Ergo doesn't fit my torso length well. Some moms says that the Beco is challenging with an ample bosom, but I didn't find that to me true for me. I also like that the Beco can fit a newborn well and be worn into the toddler years. Ergo requires an insert (or rolled up blanket) for a newborn, which doesn't lend a "hands free" feel. But, the Ergo has a wider base and so it stays knee-to-knee on a toddler longer (not that knee-to-knee fabric is as helpful at that age).
If you want a SSC (buckles) to use for a newborn, one with an integrated newborn seat is an easier choice than one with a newborn insert (like ergo). I have a chimparoo trek, got it around 3 mo, and it still fits my 27 mo. Ergos are outgrown faster because the carrier shell is shorter than most. One of the Becos has the newborn harness, but you're best off to try on a bunch of different brands. Tula and Onya are good ones too. They all fit a tad different.
If you're not set on buckles, a k'tan is like a moby with no wrapping, it just slips on and baby slides in. Very supportive. And ring slings are quick and versatile too. See if you have a local babywearing group, some of them have lending libraries.
I love my beco Gemini, but also use a maya ring sling. It depends on the situation! The ring sling is quick and easy for newborns. Ditto the international Babywearing group. You can get so much great info there and try on and rent different carriers!
I love my ergo but I haven't tried the other so I can't compare. The only thing I would say is it wouldn't be the best in the summer for an infant because the insert and the carrier can get warm if you have a little sweat bucket like my baby but otherwise we had no problem using the insert. It held him all tucked in safe and was completely hands free. He is still in the age they say to use the insert but he is getting a bit big for it so we just use the pillow (that they sit on till they are bigger) now. It is comfy and the straps aren't confusing. We also use a Moby. I agree you just have to go try em all on. Buybuy baby let's you try them on and I believe babies r us may as well.
I had an Ergo and it was fine, but I would have prefered a Beco since the baby can face either forward or backward. Both my kids loved facing forward as they got bigger, so I wound up using a Bjorn way longer than my back could handle and saving the Ergo for cuddle/sleepy times.
Re: ergo vs beco
More Green For Less Green
If you're not set on buckles, a k'tan is like a moby with no wrapping, it just slips on and baby slides in. Very supportive. And ring slings are quick and versatile too. See if you have a local babywearing group, some of them have lending libraries.