Over the past year, we've tried a Moby/Sleepy Wrap, mei tai, ring sling, and structured carriers of various brands (Infantino, Ergo, and Beco). While that isn't everything out there on the market, its a good sampling of the various types of carriers.
Now that C is bigger (almost 24lbs and 31" tall) our options and favorites have changed. For instance, the Sleepy Wrap (which we LOVED) is more of a snuggly, womb type environment - not what a squirmy toddler is looking for. He wants to see the world when we're out and about! While yes, there are high back carries that would give him the vantage point he's looking for, the Moby/Sleep wrap is not recommended for them. Despite its 40ish pound weight limit, after months of use and stretch, it can feel less than secure when tied that way.
If you like the wrap style and want to delve in the world of back carries (which are comfy and very cool), you'll want to check out a woven wrap. The colors are amazing works of art and they are incredibly breathable, making baby wearing comfortable even in the summer. I've been looking for a good deal on a woven, but until then, the average cost of $120 isn't in the budget. Yet.
Some carriers just weren't for us - I found the ring sling to be uncomfortable (I have a bad shoulder and the the single shoulder thing just didn't give me enough support) and the Infantino brand carrier to be too warm. Last summer, I found a mei tai carrier at a consignment sale for $3 (!!!), but C is getting a little too heavy for it. It has a beautiful brocade panel, too. Booo!
Our current favorite remains our Beco Butterfly, which has easily gone from newborn to baby to toddler. It is comfortable and I can wear him for extended periods of time without a problem.
11 months @ 21 lbs., 28"
14 1/2 months @ 24 lbs., 31"
Now that C is bigger its actually much easier to put him on my back without help. I can just toss him up there, bend over slightly, and wrangle up all the straps while he's balanced on my back. He's used to it, so he doesn't try to dive off while I'm getting him situated.
Why not just use a stroller? We definitely do at times, but sometimes its just not possible (i.e. the county fair with grass/gravel ground, hiking, crowded city street, etc.) and until he starts walking, this is way easier.
The bottom line recommendations:
For a newborn, a Moby Wrap or Sleep Wrap is perfect. Soft, comfy, easy to launder, and a perfect way to carry around a snuggly baby. For an infant, we loved our Beco, mei tai, and sometimes the wrap. For a toddler, the Beco (or my invisible dream woven wrap) is the way to go.
If you can't spring for multiple carriers, getting one that will last for a while is key. While its not quite as womb like, a mei tai or Beco can safely and comfortably carry a child from birth to toddler hood.