Plenty of good bats out there. My youngest just turned 7 and he's swinging the Rawlings Prodigy in 26/16. He's not big...4'3" and 54 lbs. There are plenty of more expensive bats than that one but it's the hottest bat in that price range and has out hit much more expensive bats. It has a certain sound to it that really catches the ear. My oldest (8) is swinging a 27/17 Marruchi Cat 6 but I can't tell any difference in it and the Prodigy at 1/3 the price.
Agree completely on the Prodigy. Definitely has a ping to it but it's certainly hot for the price. Good bats are plentiful but in the end at that age I haven't seen any bat make that much difference. Maybe a little difference but swing form, power, and bat speed are what makes the difference as long as it's a decent bat. My son just turned 9 and still has a prodigy that he uses some. He also has a bat that cost 3 times as much and I can tell very little difference on an equally solid hit from either bat.