Have you played them both?
I'm a big fan of fish tales and think it is very fun for casual players. On one hand it can be a drain monster, but on the other hand, it has great sound, humor and rules that are quick for new players to pick up. It also has the boat ramp which provides an obvious target for new players and that is satisfying to hit. I don't think casual players mind a tough game so much if it is set on Free Play.
For more experienced players you can try to get the jackpots during multiball and collect the Big Fish. It also has a great video mode. Definitely has that "just one more game" pull to me.
An all around great package in my opinion.