it depends on your frame and your needs, if you are 180 cm tall and have some curves, then, mini, probably, will look a bit too small on you, or, if you are 150 cm and very slim, then, a regular City might feel a little too big for you.
i am 164 cm and i wear US size 8-10, i have 1 mini, 1 S and 3 regular Cities, i have use for all of them depending on the purpose.
Mini is enough if i do a quick errand and need a small wallet+keys+phones and a sanitizer.
S is good for anything, but it won't fit the docs, or full size planner, if you think of using it for work.
Regular is roomy, but not too big, i easily used it for work, or family outings, e.g. going to the mall with the kids (extra tissues, a bottle of water, light cardi, etc)