Personally I only will wear capris... I am pretty short (5' 4") and cropped pants just look ridiculous on me! I think taller women can wear them and they do look much dressier than capris. But for me I feel a lot more comfortable in capris.
Also in terms of being dressy, I think it really depends on the fabric... obviously jeans are more casual but it you go for a white denim or linen fabric it will look nicer regardless of whether they are cropped or capris.

Hope thats helpful... it's really about what your most comfortable in!