I LOVE wearing my baby. It keeps my baby snuggled close to me while keeping me hands-free. However, deciding on one carrier to suit my need was difficult, and I had to do a lot of thinking and research. To save you that trouble, here's a breakdown on the carriers and which one suits you.
Tandem carry: If you need to tandem carry, then your best bet is a wrap for the younger baby and Soft Structured Carrier (SSC) for the older one. Don't use a ring sling as the SSC's straps might dig into the ring of the carrier.
Wrap: The evergreen babywearing technique that a lot of mothers swear by. Using a wrap, to me, is like an art, and a tad bit time consuming, especially with older children. However, it is very comfortable with and for newborns and young babies.
Ring sling: Another carrier suitable for young to older babies. Ring slings are light, airy and a boon for mothers with babies who want in and out frequently.
Soft Structured Carriers (SSC): A MUST with heavy toddlers, I say. These are very safe, secure and easy to wear. Might not suit newborns and young babies, but this is the best carrier for toddlers.