Buddhism. I've been practicing for 14 years now and had my enshrinement ceremony 13 years ago.
Why?
Because it doesn't allow you to blame outside influences for your suffering. You take responsibility for your own happiness. Because Buddhism teaches compassion. Because it's a continual process of learning. Because the Buddha said not to take his teachings on blind faith but to only practice Buddhism if you see the proof in your own life. Because the purpose of life is happiness. Because researchers have studied the effects of meditation/chanting/mindfulness on the brains of Buddhist monks and even lay persons who have only practiced for 6 weeks and they can measure the changes in the brain.
