When choosing a carrier it is important to consider how the child is supported. Unfortunately there are many carriers which do not mimic the way a baby is held in-arms. So many babies are carried in carriers that force their weight onto their crotch, rather than supporting them from their bottom.
Good carriers support a baby from knee to knee, upright, against the wearers chest or back. For front carries it is important to keep babies “close enough to kiss”.
Here is a great poster.