Well, let's do a direct comparison:
AC: Equal. They both contribute (arguably, Wis is slightly more useful as Dex bonus to AC is lost when flatfooted)
Saves: Equal. Yes, you get Improved Evasion at 9th level, but with Evasion, you could argue that Reflex saves become even more important: you have the potential to negate all damage, whereas most people against most spells are only negating half. When you pick up IE, it's as important as a Reflex save to any other class.
Skills: Dex edges it. Wis is important for Listen and Spot, but Tumble, Hide, Move Silently and many more as Dex-based.
Feats: One up to Wisdom. Dex is handy for Combat Reflexes, and make sure it's not too low, but otherwise Wis rules the roost- particularly with Stunning Fist.
Attacks: Has to be Dex. Not only does it contribute to ranged attacks (which admittedly are infrequently used by monks) it can be used with Weapon Finesse to your unarmed attacks.
Special: Dex bonus to Initiative is so useful, especially at high levels, especially when there are high sneak attack rogues, Expert Tactician fighters and assault wizards running around.
The final outcome: Dex wins a slight victory.