I received several different styles of infant carriers and slings when I was pregnant with Claire. I tried each one and never felt completely comfortable wearing them; either I was afraid that she was not secured safely or the awkward positioning hurt my back. Eventually, my mom made me a "Moby" style wrap (google it for instructions - so easy to make!). It's basically just 15 feet of cotton fabric that you can wrap around your body in a variety of ways. You can carry a newborn against your body, which is great for Kangaroo holding. For older babies, they can be facing outward or carried on your back. Toddlers can even be carried on your hip with this wrap (although I've never tried that -- too heavy!).
I'm a huge fan of "On Becoming Babywise" by Gary Ezzo, and the Babywise philosophy does not advocate wearing your baby 24/7. However, I've found that with an active toddler at home, I have much less time to hold and cuddle with Liam than I did when Claire was a newborn. While wearing him, I can get things done around the house or play with Claire and he still gets some Mommy cuddling time. Just thought I'd mention it for other moms who may be in the market for a new sling!