I have the medium flap. I like the slightly larger look and sizing on my 5' 4 (around 161 cm) frame. Also I ended up getting a mini flap and though the mini and small were too similar in what they fit.
I think if you plan to add a mini flap to your collection in the future, consider the small and mini will fit similar things. Check youtube reviews.
I think if you plan to add a mini flap to your collection in the future, consider the small and mini will fit similar things. Check youtube reviews.