Is it from newborn or from bigger? To be honest there isn't really one SSC I'd rate above the others. They all have pros and cons, and it is especially difficult from newborn.
Some other alternatives are the Boba (the 3g version is from birth, the 2g from about 4-5 months). I like how it is thinner than the Ergo/Manduca but still very supportive, and it has foot stirrup things that keep it supportive for a bigger child longer than most other standard sized carriers. Can't cross the straps on the back like the manduca though. I haven't tried out the 3g with a tiny baby though....it looks okay but not ideal. But then I don't love SSCs for tiny babies in general to be honest.
The Ergo is good for 4-5 months + but I think the infant insert bit isn't great at all, especially in hot weather.
The Connecta is less structured than other buckle carriers. Can be used from newborn without the need for an extra insert thing - because it is softer you can cinch in the bottom of the carrier to make it narrower. But it won't last as long as say the Boba or Ergo or Manduca for carrying a bigger child.
From newborn, in an ideal world I'd suggest buying a 2nd hand stretchy, then selling it when baby gets to 4-5 months and buying a SSC instead. It increases the range of SSCs that will work easily without them having to be newborn-suitable, and is comfier and cosier than a SSC for a tiny baby imo. But I do understand that some people would just prefer buckles from day one because they don't like the idea of a wrap, and the newborn-suitable SSCs will do the job. Another possibility I love for a newborn is the Hoppediz Hop Tye - more shaped than a wrap, but still very snuggly, but still no buckles.
FWIW when my sister had a newborn I got her a Connecta and a stretchy, to cover all eventualities!