K.L.
I had/have both plus a sling. I'm 5'8" and 120lbs (slight) and the baby bjorn just didn't fit me right. I couldn't get it tight enough. Worked great for my husban though. We got the Ergo later my son was at least a year old by then. Fit me and my husband well. I liked that I could do a front, side, or back carry. My son is nearly 4 (and about 40 lbs) and we still use the Ergo when we go on trips. Longer useful lifespan than the Baby Bjorn. I gave up the BB at about 5-6 months of age and started using my sling since I could hip carry my son. Then late switched to the Ergo - could have use it earlier though.