We have only ever used slings with jocelyn (and she's now 15 months and 26lb 6.5oz so that's testament to how good they are!!)
We bought 4 types:
1st - premaxx sling, don't bother - we couldn't ever get her comfy and I sold it on ebay after she was 8 months old and we'd given up trying
2nd - ring, again, don't bother - I know they work for some people but I found they really strained my neck and just weren't comfy
3rd - Kari-me wrap sling, oh my life I couldn't praise this highly enough!! We used this from birth until she was about 10-11 months old, it was absolutley brilliant! Very comfy, allowed us to fully do attatched parenting, was brilliant for feeding on the go, lovely for carrying her in all day and an absolute godsend during colic!! We are using the same sling for wibbly and, again, have no intention of buying a buggy! This sling is wonderful, it's a stretchy wrap sling which means you actually tie it quite tightly to you - the weight of the baby is what creates the pouch for her to lie in. As a result there was no strain to my back/neck/pelvis and I have had a lotof problems with all 3 in the past so that was great for me! I preferred the karie-me to the moby as it is stretchier so it made it easier to tuck her head in when she fell asleep and also kept her warmer too in the cold but not too warm in the heat!
4th - a Mei-tai equivalent. We're still using this one now - we still have her on our front but that's because we want to be able to talk/interact with her although I don't know how many weeks I'll be able to keep her on my front before she has to go on my back!! We started using this at about 10-11 months and will do so until she's fully walking which won't be long now!
Some pics for you
6 days old - going home! (Kari-me sling)
2 months, 12 days old - legs sticking out now!
2 months 26 days, facing outwards!
She's in there somewhere! Last time I was able to wear her this way to sleep, 3 months and 23 days
5 months, 17 days, facing outwards
6 months 6 days, first time in the mei-tai
7 months, 3 days
7 months 18 days, asleep with daddy
No I'm not pg - it's a pickle! 7 months 13 days
Disadvantages of sling wearing - icecream being stolen! 10 months, 23 days in the mei-tai
12 months, 21 days on daddy's back
a day or two shy of 14 months
I know it's loads but it gives you an idea of their versitility and just how much slings can be a real contender for baby transport without the need to spend hundreds of pounds on a buggy!