I've had a few carriers, mainly through presents and hand me downs. So I'll list some pro's and cons. Hope it helps!
Baba sling - a pouch sling with adjustable straps and buckles for easy on and off.
great sling for just chucking on for a quick trip to shops, or hanging off the buggy for "I don't want to be in the buggy" moments. Easy to adjust, so both me and my OH can use it. Like the clips, means that if LO is asleep you can unclip it and place them down to sleep without waking them up. Downside is that it is not truly 'hands free' as I never feel that LO is 100% safe in it when wriggling!
Baby bjorn- great when they are little, good head support, easy to wear and really 'hands free' so was great in tesco! LO slept in it and loved the forward facing position when older. Downside is that by 4 months I was struggling with it due tout causing back and shoulder pain, and my LO is light at 13 lbs! I don't use it anymore. My friends have made similar comments about back pain.
Peanutshell- a non adjustable pouch sling. Bought it on whim, is White with blue swirls so really pretty... But have not been able to use it!! The sizing chart recommended I have a size large, as I'm tall, but it is way too big for me. I'm 5'9" and a size 12.
Ergo baby - recent purchase to replace baby bjorn. Can carry on front back or hip. It's very secure, and comfy. Again- Truly hands free even in hip carry. Thick padded straps make is really comfy and the waist band distributes the load better than baby bjorn. The downside? It's expensive, and you need a newborn insert for up to 4 months. However I think that ifyou compare it to baby bjorn- which costs £55 ish new, you'll get so much more wear out of it. I wish I'd known about it sooner. It also has a really good re-sale price on eBay.
So.. Hope this helps. Hopefully other folks can tell you their experiences about these carriers as every one is different! Also ifanyone has made the peanutshell work for them?
