Baby Izabella is almost one-year-old and my favorite way to wear her is the Ergo carrier. This carrier evenly distributes her weight across both my shoulders and also through my hips. I fasten it around waist and then set her in before fastening the shoulder straps. This allows me to easily take her out while we ride on public transportation, where she inevitably wants to explore and/or interact with other passengers, and easily get her re-strapped in when it is time to leave the train. The carrier is also wearable on the back, which is great for when my husband or I prepare dinner. It can also be used on the hip, but this carry is not so convenient as you have to readjust the straps. I have found this carrier to be the most "hands-free" and the best for long walks. I also can nurse in it.
When Iza was younger, and thus weighed less, I got a ton of use out of the Over The Shoulder Baby Holder. Although I like the fit of a ring sling better, the OTBH is easier and quicker to use. I still use it frequently around the house for a quick hip hold.
When Iza was teeny tiny I really liked the Moby Wrap. This is the long piece of stretchy fabric that can be tied in many positions. I found it more comfortable and secure than the OTBH, but way, way more cumbersome to take on and off.
So there is no ONE best carrier in my opinion, rather you need a variety depending on your body type, the age of the baby, and the purpose of the carry.
In Boston there is a great organization called The Boston Babywearers. They maintain a lending library of around 20 different slings that you can check out for a month at a time by placing a refundable deposit. (This way you can avoid dropping the hundred bucks are so on a carrier that doesn't work out for you!) The women who run the group are experts and will happily provide hands-on help to learn the ways of each carrier. They also run a listserv that has been enormously instructive. I have only made it to ONE meeting, but have learned a ton just by reading the listserv digest. You can check them out here: http://www.bostonbabywearers.com/ I mention this group because I think it would be great to have more groups like them across the country!
Slightly intimidating.
13 years ago