Disclaimer - I have done my Babywearing Peer Supporter course, but I don't have the actual certificate yet as I haven't completed my coursework.
You are right to stay away from the Baby Bjorn. They effectively support the baby by grabbing the crotch and offer no support across the base of the bum or spine. They also encourage forward facing which is again a no-no. Babies' spines are naturally C shaped until they are about 1 year old, and wearing a baby on your front with the baby facing forward forces their spine in the wrong direction. They are also thick and bulky - when you carry a baby they have the benefit from your body heat as well, and it's easy for them to overheat if you're not careful. They also don't work well much past the small baby stage.
You need to support the baby from knee to knee, with their legs in a "frogged" position; see here:
http://hipdysplasia.org/developmental-dysplasia-of-the-hip/prevention/baby-carriers-seats-and-other-equipment/Ergo carriers are a good option. They are popular and fakes abound so buy from someplace reputable, such as John Lewis. You might also want to consider a Manduca or Tula baby carrier. You can also consider a Connecta - for summer use they do a Connecta made out of solarweave fabric which is very lightweight.
You might also consider wraps - there are stretchy wraps and woven wraps. Stretcy wraps you tie about you first, then shove the baby in, woven wraps require a bit more dexterity as you tie they around the baby. Woven wraps have the advantage in that you can use back carries and they can cope with much bigger babies and toddlers. MissS is 15 months and I routinely use a woven wrap for a back carry for shopping etc.
Advice on carrying your baby safely can be found here:
http://www.schoolofbabywearing.com/check-your-ticks/Also you may have a sling library near you which should have lots of different types to try on and loan.