What is the most effective form of birth control? What is the most effective form of contraception aside from condoms?

Abstinence. Abstinence is actually the only 100% effective form of contraception. Condoms are actually not the most effective form of contraception either given the chance of breakage of misuse or forgetting to use them every time, but they do help protect against sexually transmitted infections. Other forms that are equally or more effective if used properly are iud's (intrauterine devices) which are small pieces of plastic or copper that are inserted into the uterus in the doctor's office with minimal discomfort and no anesthesia needed that can stay in for 5-10 years and be easily removed if future pregnancy is desired, a vaginal ring that you yourself put into the vagina once per month, a contraceptive patch that goes on the skin. There are also permanent procedures including tubal ligation (tubes tied) and essure for women and vasectomy for men when people are done having children. There are also a bunch of different kinds of birth control pills that are highly effective if taken correctly. There are a few other ones as well, but aren't used very often.
IUDs and implants. You should consider long-acting reversible contraceptives (larc)--2 types of iuds and a small rod placed under the skin. All very effective (the most effective methods--as effective as sterilization), and last 5 or 10 years (iuds) or 3 years (implant). Low rates of side effects, and the hormone iud has low levels of hormones and benefits of lighter periods.