Copper
"I had paragard placed over 2 years ago after constantly experiencing negative side effects from ALL other forms of birth control. 
Insertion was awful. AWFUL. It felt like I was in labor all over again and missed a day and a half of work because of how severe the cramps were.  The side effects I noticed right away were VERY heavy periods and VERY painful cramps. Then, within a year, I noticed I had become very restless, moody, low energy, and constantly bloated. Thinning hair, tired, some weight gain and unable to sleep. 
I just had my paragard removed over a week ago and already notice a huge, positive difference in my body and mind!!! I didn't hate paragard, but definitely won't get it again."