I like (and am addicted to)..
Manual blocking and chambers, the metal-on-metal clang and the feeling of it
Hewing down foes, the sound and feeling of going through armor and sinking into flesh
Feinting and just swinging a weapon, appreciating the individual physics of the weapons in the open-form, four-direction combat system
Killing archers, especially unawares or when trying to run
Felling horses on the move
A good duel against a seasoned warrior, of course
Team work, especially clan battles in the ENL