Get the game you want most, the kids will love having a pinball machine either way. My kids don't relate to AC/DC, and while the music is lively, AC/DC is somewhat of an adult theme.. an old band like that just doesn't seem to be the best choice for kids.
Tron is made by disney and the gameplay is fun.. light cycles, a spinning disc, and arcade machine, and a third flipper make it a lot of fun. The kids will get to know what to shoot for and will have a lot of fun. And I think Daft Punk is much better music than AC/DC when talking about kids.
While I'm not a shrewd, I don't know if I'd care to have my kids running around singing "a whole lot of Rosie" or "Hells bells". Again, fine for me personally, not so much what I want for my kids. You may not care. But I do think Tron is a better pinball game anyways, and that's what really should help you make your decision.