Xarius...as Matt said, it does depend on taste. I've only played the Nova and Hyperior patches to any extent (and of course regular EFS)
I play regular EFS for flashbacks and nostalgia of when I first played and loved the game.
I play Nova in multiplayer games.
I play Hyperion for single player, and have played some multiplayer games. It is very difficult. It also has a lot of cool applications of new ideas in it. Nova is basically the "vanilla", and Hyperior is kinda the version with sprinkles
Both are equally good, it all depends on what you feel like playing.