Copper
"I've had mine in for about a year now and I bleed after sex everytime and my period lasts for about 10 days and is extremely heavy to the point where I have to wear a super tampon and a night time pad and I have to Change them both every two hours! I get such bad (contraction type) pain throughout the month, I also had funny smells and bloating! I feel like I'm not in control of my body as my periods and other things prior to the IUD were very normal! 
I've just arranged to have it removed and I can't wait!
I wouldn't recommend this as if it goes wrong like it has with me it's another procedure to get it out!"