I think their clothes tend to hold up better than a lot of the other brands. Don’t get me wrong, my kid has clothes from a variety of places including Target, Old Navy, Lands End, and Hanna Andersson, but the Hanna clothes don’t look nearly as worn as other brands after multiple wearings and washings. They offer slim options for a decent number of their pants (which are hard to find for kids unless you only buy leggings) and the drawstrings in pants actually work - it’s not just a decoration.
I do buy a fair amount used (Facebook groups) and also sell what my kid has outgrown. Occasionally I’ll buy new, but it has to be a really good sale/discount for me to do that.