Baby sling or baby wrap?

Babywearing is a new part of my parenting. I always believed in holding my child, but I didn't really know about slings or wraps for my first 3 children. Oh, the agony it would have saved me with Kaytlin!
I started buying slings with my 5th child. I tried two with no success. They just did not work for me. I kept them and tried again with Trinity with no success.
I really wanted to wear my babies, so I kept trying.
With Sam I bought this Over The Shoulder Baby Holder and it worked for us! Finally! It still was a bit bulky for my tastes, but it wasn't painful and it wasn't akward.
I needed something that would give me both hands free and would not make my back ache, so I kept searching. Even the Maya Wrap ring sling did not work for me, it really hurt my shoulder, though it was quite pretty.

Then I bought my first wrap. I can have him face me or face away from me or have him on my back, or cradle him like a sling and even nurse him. He is so secure that I do not need to hold him at all.
Sam has a definate preference for the wrap. He likes to face out and swing his legs. You can see a few different ways to wear your baby in a wrap at Sleepy Wrap.
I noticed right away that when I wore him, Sam was much more involved in the world. He would have conversations with us, he would watch us closer, he would try to touch the trees and flowers and birds as we took walks. In the stroller he would hold a toy or cup, but he didn't get as involved and never tried to be part of the world, he just sort of watched it go by.
Either way you go, sling or wrap, you baby gets so much benefit from it. Research from Dr. Sears shows that wearing your baby produces more social babies and also smarter babies. Babies who are worn cry a lot less, also. I do not believe in making a baby cry it out, when you can just wear them and they are happy and learning at the same time why would you want to make your child cry?
I like both slings and wraps for the benefits to baby. I prefer the wraps for long distance wearing, like walking the State Fair. But I prefer the sling for times when you will be taking the baby in and out, like at family gatherings, because the sling is definately less complicated. I have not tried a pouch, yet, but would love to. My next purchase will be a Mei Tai so I can carry a toddler more comfortably on my back, the wrap is too complicated to do by myself on the back.

What is your favorite babywearing item? Why do you like it best? Have you noticed a difference in your children that you wore and didn't wear?