Parry is the best, and only defense for 2handed weapon users. I have a level 42 Hero with 47 parry (with items). As a two handed user if you dont have parry, you tend to turn into a mana sinkhole for healers because the monsters will always hit you. With parry at level 47 I've had numerous instances where I've parried every blow in a fight, once up to 9 times in a row in a battle. This takes considerable damage off you when you're dealing with purple and red creatures.
If you are using a one handed weapon, parry is also very useful. In order to max out the creatures chance to NOT hit you, if you do the math (yes math is useful) keeping parry and shield up at the same level will give you more a chance to evade/block/parry a move in battle. Since you dont have to MAX either of these defense moves, you can put a point in each shield and parry each level, thus gaining 1% to your block/parry instead of .5% by maxing one defensive type. Granted you want to get shield up a tad higher for the styles.
My two cents.