I have used a Moby wrap and found it great to carry Maddi in and still have my hands free!
I find it sooo comfortable and she like it too. A wee bit fiddly to get on at first but once its on i can pop her in and out when ever I like.
I have used a sling but feel so much safer with the wrap and not like shes about to fall out.
Its also really handy because it can be used to carry them in different positions. (I even managed to walk around the zoo bf'ing Maddi , without anyone noticing, while I pushed Keira in her push chair

) And DH can wear it too!
I do have an ordinairy front pack (baby first comfy cruiser, i think?) but have never ended up using it.