If I had to choose between those 3, I'd choose XFO. FOOK is more of a bugfix/item addon mod rather than a gameplay overhaul (like XFO) and I don't even know what Earache is (been away from the community for awhile).
My personal choice, however, is Arwen's Realism Tweaks, as I feel it's the best balanced. Though, I do warn you, hardcoe mode with Arwen's is really... well... hardcoe.
Also, keep an eye on Project Nevada. I'm sure after they release some of their rebalancing modules, it will be quite an amazing mod.