Which of that sounds far-fetched for you? Both rankings go against what my gut tells me, and I'm uncertain if they are a good representation of what we know, but then again I don't think you can have a good ranking right now – you create several that represent different sets of the things we think are important. I don't see how they are in any way far-fetched.
My only complaint is that they limit themselves to two indices. There should be at least one targeting conditions for known life, one that favours liquid water for example. Europa and Enceladus should top at least one ranking. Callisto and Ganymede also might have subsurface oceans.