Which IUD to choose?

I've been on birth control since age 16. I've tried three different pills because of complications with each one I tried. I never had acne or weight gain before being on the pill. My gyno said that it could be caused by the added hormones, and suggested an IUD. I'm 19, and have never had kids. I know there are three IUD's: Mirena(hormone), Skyla(hormone, but smaller), and Paraguard(copper). I will be getting my IUD inserted August 3rd and chose Paraguard. Thoughts and opinions? I'm tired of mood swings, unnecessary acne, and the weight that I can't get off.