Hmmm, I think there must be some local influence in this too. Growing up in the UK, I can recall hearing gazillion far more frequently than zillion.<p>Also, younger children would often also say squillion for a number even bigger than (ga)zillion.
> It's also perhaps worth noting that the -b- key and the -z- key sit right next to one another on the 1895 Linotype board<p>It's like `zomg` or `pwn`