What is the best birth control (most effective)?

Birth Control. 1) abstinence - but fails a lot 2) hysterectomy - but a little invasie 3) the Mirena (levonorgestrel) iud - with a failure rate of about 1/2000 its even better than having your tubes tied, which still fails at a rate of 1/200 (true!).
IUD/Implant. Regardless of your age, blood pressure, family history, or reactions to other birth control, the most effective and safest methods of birth control are long-acting progestin-only methods, such as the implant or the hormonal IUD, which decrease rates of endometrial cancer and decrease bleeding. They're safe, reversible, and don't affect weight gain/mood. They're almost as good as getting sterilized.