There are several company's that are really good brands like DeMarini, Easton, and Combat.
The website in the related link reviews 42 Senior League & Youth
Baseball bats by these companies: Anderson, Baden Sports, Combat Sports, DeMarini, Easton, Louisville Slugger, Marucci Bats, MetalStorm, Miken, Nike, Rawlings, Reebok, Rip-IT and Worth. Updated for 2013, the 42 Senior League / Youth bats are reviewed by Managers with 1,900+ reviews from Players, Parents and Coaches.
The real answer - most of the top companies have some great bats, some good bats and some duds - and some that perform well but are not durable. What you should be asking is which bat is the best for me. And the answer is - depends: Are you a a power hitter or a contact (line-drive) hitter? Do you have slow bat speed or fast bat speed. In general, power hitters want end-loaded bats with little flex (e.g., one-piece bats) while contact hitters want balanced bats with more flex (e.g., two-piece bats).
See the related link which also provides Top Rankings of the Best Senior League & Youth Baseball Bats in several categories - Overall, Power Hitters and Contact Hitters.