I was skeptical of the Moby too when I was pg last time. I thought..seriously? ALL that wrapping around? But after reading a lot, and so many people thought they (meaning the wrap kind of carriers) were the most comfortable, I decided to give the Moby a try...and I'm REALLY glad that I did. I *LOVE* the moby wrap. *LOVE IT*
Once you've got the inital "wrap" figured out (and it's not hard, it just looks a little confusing at frist), there are so many possibilites to customize the fit and carry for what will work for you. I used it all the time...until my wee one wasn't so wee anymore and he got heavy.
Then, I switched to the Ergo. I am a HUGE fan of these carriers- NO back pain because of they way the weight is distributed. I LOVE this carrier too, and it's still in my car (my son is almost 21 months) in case we ever need it while we're out. I really liked that I could carry him up front until after he was a year old (he never really liked to be on my back for more than a little bit, he preferred to see where we were going, I guess!) and it didn't bother my back at all (and he was a BIG boy!).

I, too, had a hotsling, but it was too small so I never used it.
I also had a ring sling, but I didn't use it too much so I sold it on ebay. I am looking at getting a different one this time though!

I also have a hybrid sling/pouch made by a local gal, and I DO like that one- especially as a hip carrier when he got old enough to sit up, and for naps during the day. It did hurt my back after a short time though (not so much in the hip carry, but in the asleep in the pouch mode).