What makes the Giants number one is their depth. They've got four announcers and they're all excellent and funny, too. Scully is Scully - though I listened to a Giants-Dodgers game from 1978 on my iPhone today, and he's definitely lost a few steps - but the other three Dodger announcers are decidedly meh.
I also disagree with the White Sox being last. I find Harrelson more amusing at this point than anything else, and Stone is one of the best half-dozen TV analysts in the game. There's so many crews who are boring AND bad, and say what you want about Harrelson, but he's not boring. The Cards are dull - McLaughlin is just an announcer guy and Hrabosky is a miserable, frequently wrong asshole. It's like having an Angry White Guy from the Tea Party in the booth. McCarver will be a distinct improvement - at least he's genial. Physioc and Hudler are also really, really bad.
The Padres deserved to be ranked higher due to Enberg. He might not have had the peak of Scully, but he's lost fewer steps. The man's 80 and still brings it every night.
I was also surprised the Mets finished behind the Orioles, given how the New York media (deservedly) loves the Gary/Keith/Ron trio. The Orioles are good, but I'd probably put them fourth.