I've used an Implanon implant in my arm for 5 years. Each implant lasts for 3 years ... it secrets progestin only, is safe, inhibits ovulation and is extremely effective.
I've had no side effects, no weight gain, nothing.
The pill has always been a disaster for me. Each time I try it, it is usually a progestin / estrogen mix which makes me vomit without warning, gives me migraines, stomach cramps, mood swings AND makes me fat as well. The pill does not work for me
As the US does not provide the implant at a reasonable cost, I'm going to opt for the Depo Provera shot. It, again, is progestin only and lasts for 3 months per shot. I'll wait and see how it goes ...
Good luck in your choices

jazz