Old Billy was just a one dimensional stereotype that remained moderately entertaining at times but was mostly annoying.
But back on topic, I'd say SHAZAM isn't that suitable for children (it isn't unsuitable but not really targeted towards them). BQM's Batgirl is a good choice but avoid Simone's and Fawkes' garbage as it isn't suitable for anyone. Tiny Titans and Superman Family Adventures are also good choices. Lil' Gotham is amazeballs. Definately get that when it hits trades.