Ooh I thought I had this all sussed, until this week.
I loved a stretchy wrap when DS was small. I could use it up until he was about 7-8 months comfortably, and I am small and weedy. Make sure you are tying it tight enough, it's supposed to be as tight as a skintight top when you first put it on, then you put the baby in and it will feel slightly uncomfortably tight for the first 5-10 minutes but then as they and you move around it sort of loosens it up a bit and is very comfortable.
I thought I would graduate to a woven wrap, but DS was so wriggly I could not do it up around him, especially on my back, I could never keep him still enough and it took 3 of us to get him in it, which was no good.
I bought a ring sling to wear at a Christening (matching my dress ) but didn't get on with it as it was only on one shoulder and I found it hard to adjust, so it got left in the back of the wardrobe for ages.
I bought a Wilkinet thinking that something more structured would be good, but when I got it it seems it's not really suitable for toddlers, only smaller babies.
I have just ordered myself a toddler Patapum (DS is 15 months and I have been mainly using the pushchair and occasionally using but getting frustrated with my other slings) and am looking forward to that. I quite often give DS piggybacks around the room which he loves so I hope he will be more willing to go on my back.
Also, this week I have been using my ring sling again around the house and without really thinking, scooting DS around onto my back and it is fantastic! But does pull on my shoulder so I could not use it for long at a time.
Am anxiously awaiting the Patapum as I think that a stretchy wrap and then soft structured carrier (Ergo etc) is probably the best value for money combination, so hoping it works as well as I am expecting.