Baby Wearing Help!!!

Hi friends!!

I need your help. We have been looking at purchasing a carrier/sling for B3. In addition to the benefits of baby wearing, I just know it will help to be able to have my hands free with two other guys to take care of and play with.

However, I can't decide between these two:

The Ergo Baby Carrier

The Moby sling

We have a baby bjorn that we have really liked but it really really hurts my back after awhile. (like 30 minutes tops). So we want something that will be great on our backs and comfy for baby.

Both of these can go from infant up to 30-40 lbs. (which technically means I could carry West around in either. haha. can you imagine?!)
They are both designed to fit a lot of sizes, so Jeff and I could both wear them.
They both have amazing reviews and people love them.
They are quite different in price. ($105 vs $40)
But I want something that will last and something I will really use.

SO...have any of you every used one of these? Or better yet, have any of you used both??? What do you think????
I would appreciate any and all thoughts. Like right now. Go leave me a comment. I have to make this purchase tonight before our 30 day free Amazon prime trial runs out. (I hate paying shipping)

Thanks in advance.