Enceladus is where it’s at. More than the benign radiation environment, Enceladus is spouting liquid water geysers from its southern pole with heights greater than the diameter of Enceladus itself. So you don’t have to map the ocean or dig down to it to get at pre-biotic/biotic samples. You just have to fly through the geysers. And we already know those geysers contain carbon dioxide, methane, ammonia, hydrogen cyanide, ethane, and methanol — all key ingredients in life on Earth. If we find life elsewhere in our solar system in our lifetimes, it will be at Enceladus.