While less versatile, I prefer dresses to skirts. I admit that some days I'd rather be in bell-bottomed trousers or skinny jeans but that's another story.
I generally prefer dresses because they're a great deal easier to put on, are slightly more forgiving in shape, and lack the need to coordinate with a top. For me the main draw is the greater comfort around my waist. I would generally look for dresses I can put on by stepping into them.