What ever system works for you, is the right system.
Is Haganah good? Yes, and so is Krav and at least two other systems I can think of.
I would go watch a class, and take a free class if it is available. I would also check out more than one school, as well as more than one system. See if there are Krav, Haganah and other systems taught in your area.
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"If you're gonna be stupid, you better be tough."