Maravich is a terrible choice. I don't see how he was included in the NBA top 50. I remember when people bitched about Bill Walton being included, but at least there was a time in NBA history when Bill Walton was the best player in the league. Maravich can make no such claim. Great story, great player, but the production just isn't there.
I only saw the 1980's Sixers Erving, and I always thought he was overrated. He was more of the "elder statesman" of the team than the true superstar (Moses Malone). And those Sixers teams were really loaded with great players. I've read that Erving was dominant in the ABA...a great scorer and rebounder and defender. So I'd put him in the top 25, maybe top 15, but not a top 10 guy, IMO.