I began "wearing" my babies almost ten years ago. The first carrier I ever tried was the OTSBH. I checked it out of a lending library that my lactation consultant had. I was in school at the time, and it became a life saver as I walked the two miles to school and sat in on my class with my newborn son. I soon purchased my own sling, but I choose a Mayawrap. The padding of the OTSBH made me sweat a little too much. My son was a big child, so having this sling was so helpful. There were not a lot of people around using baby carriers, so I stuck out quite a bit with my bright green and blue Maya, but there was no way I was going without it!
My Mayawrap got me through three babies, when I finally gave it to a good friend who had given birth to her fist child. During this time, as "new" baby carriers were being developed and marketed, I experimented with many of them. I can tie a baby on with most anything, and have often just used my coat in a pinch. My favorite carriers are the ones that are the least complicated, but versatile and comfortable. If you can only get one carrier choose between a ring sling or a structured carrier like an Ergo. I recommend that you have a few different types on hand, as you will use them for different things.
Personally, I have found that the structured carriers are my favorite. Once your baby can hold their heads up well (and even before with certain precautions), these carriers are the most convenient and comfortable of them all. I prefer a non-fussy one, like the YAMO (sadly you cannot purchase them in the US anymore), but there are other options available, like the patapum, ergo, and beco.
Next in line would come the ring slings. There are so many beautiful slings available today. I am partial to the unpadded Mayawraps though. They were the first of their kind, and they are of exceptional quality. I have tried making a few of my own ring slings, and I have never quite been able to reproduce the comfort and quality of a purchased sling. If your sewing skills are excellent, you should be able to make a custom carrier for a very good price.
Third, I like pouch style carriers and wraps. Pouches are the easiest to use, as you stick the baby in and go. The only issue you face with them is you will need two sizes to get a proper fit if you get a non-adjustable one, and if you get an adjustable one, the carrier becomes a little more complex (but not much). Wraps have a high learning curve, because they are one long piece of cloth that you tie around yourself and your baby. There are many different ways to do this, and you have to practice to find the one you and your baby like the best. Wraps are very, very comfortable are can be made from some beautiful fabrics. I have found them to be a little fiddly when I need to change positions to nurse, or when my child is in the 'up and down' phase. I love them for back carries when they are tiny and cannot hold their heads up very well yet, as the fabric cradles them well.
Fourth, are the Mei Tei. podegai, and other traditional fabric carriers. I have not found these to be comfortable, but other people really like them. I feel it it better to just spend the money on a soft structured carrier like the Patapum, your body will thank you for it in the long run. These are the types of carriers a lot of inexperienced baby wearing moms purchase because they do not want to pay the price for the structured carrier, and these carriers are pretty to look at. They like them, but I never actually see them using them all that much, and pretty soon, their kids just get too heavy for them to comfortable wear. I can and do wear my 30 pound toddler in my structured carrier without any problems.
Last, don't spend your money on the Baby Bjorn, or other soft front pack type carriers. They are not worth it! You will not get your money's use out of them. Don't bother with the slings and carriers that you find at most chain stores. They are marketed for the trend of baby wearing, but they are not made well, and they usually will not work well.
Enjoy wearing your baby!