What's the best birth control pill that will not decrease libido or cause weight gain?

Most are good: The triphasic types seem to have the least adverse effects and are as efficacious.

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. Hormone amounts are low and won't affect libido. They're safe, reversible, and don't affect weight gain/mood. They're almost as good as getting sterilized