I've never tried an ergo, and I know people love them, but I love mei tais enough that I have no reason to try an ergo! I definitely recommend a mei tai!
By the way, I don't think that a mei tai qualifies as a soft structured carrier, probably because it doesn't have much structure! Just a square of fabric with straps, for the most part.
Oh, yeah, like pp said, you can use a mei tai with your little one, just making sure you support the head with the body of the mei tai. Kelley has great instruction for carrying a newborn if you scroll down near the bottom of this page:
http://kozycarrier.homestead.com/instructions.html