I have a mayawrap and a kissaluvs, and I love them both. I had a NoJo, but it was a no go.
I found I really like metal rings better (easier to get the kid out), no padding on the railing (DS only uses the hip carry so I like it really snug and I can't get the padding through the rings), and a lose tail (great for an extra "blanket" when it's cold out). Padding on the shoulders I can take or leave, they're both fine. My MayaWrap has a pocket in the tail which is kinda neat. I have a li'l explination about slings that I print up and store in there for the people who ask me about it. =)
That's just what I've found that works for us. Of course, I still want to try about thirty other carriers. My DH is thrilled. =)