sling choices

Hello,
I'm expecting baby number three in October and loved using my sling with my
first two babies (now 4 and 6). I passed it along to someone who is still
using it so I'm looking to get another. I saw a Sling-ease made by Infantino
that goes up to 20 lbs (seem a little light since I used my other ones until
my kids were at least one year old). I'm trying to decide among that one, or
an "over the shoulder baby holder" that La Leche League sells, or a Maya
Wrap that looked nice in one of the catalogs. My old one was a La Leche one,
but wasn't new.
Anyone have any sling opinions or know of a web site that compares them? I
have a baby bjorn that I liked and used as well, but for everyday carrying
around the house and ease of entry, I definitely want another sling. Also,
do they come in different sizes? I'm average size and build and tend to get
a sore back no matter how I carry anything, though the sling was much more
comfortable than any of the backpacks or snugglies I tried.
Thanks for your opinions.
-Holly