OK I have a HAB (2 actually - first one nearly worn out!!) and a mei tai (Ellaroo) ....... and an ERGO and a pouch sling. The HAB is great for a winter baby and I used it with DS until he was nearly 6 months. Perfect for a velcro baby and for hands free. DD (summer baby) didn't like it as much (I still love it though!!) and preferred the Peanut shell single shoulder sling. From 5 months I have used the mei tai for both my daughter and my 12kg 2yo son. I also use the pouch sling for both of them (hip carry for DS and chest to chest for DD).

So really, it depends on what suits you and your little one but each one can do something different and suit what you need at different times. Try as many as you can if you have that option. Or risk ending up with as many as I have