If I had to pick between your options, Doodle Jump.. But if I could pick any that I own I'd take iDracula.
Pocket God is definitely a no no. Love the game but if I'm trapped on a desert island why would I want to play a game that would only remind me of my horrible circumstances? Had to go with Hook Champ, though Doodle Jump is infinitely replayable.
And how would you get new episodes? Same reason kills the All-In-One-Gamebox. So I picked Galcon, as it would take me being stranded on an island to master the higher levels of this game anyway! Now if you have WiFi, and can only take one app, I'd hope we could choose Safari, or App Store (so we could get more! ) Hope we remembered to pack a solar charger...
Why isn't there an 'Other' option? I could never get bored of Nacht der Untoten and Verruckt. But I'd definitely choose Hook Champ. I'm addicted to that game.