The most important aspects of Monks to me are:
1) Unarmored AC Improvement with Level - Cannot Wear Armor (but can wear magic clothing/capes/rings/bracers/gloves/boots)
2) Unarmed Combat Improvement with Level - Increase in Damage, To Hit, & Eventually # of Attacks Per Round (I would happily accept not being able to use melee weapons (except monk specific glove/hand weapons) & bows/crossbows/guns (allowing only thrown weapons) as a balance against this.
3) Monks should be the most mobile combatants on the battlefield, generally faster than other classes too. Making acrobatic leaps & running along walls & parkoring all over while still engaging in melee combat. In your system a way that might be worth exploring would be to allow to allow Monks to roll one of their Movement Related Skills (Acrobatics/Climbing/Etc) once per Round for "free" (in that they can still take their combat action or standard) allowing them to Move & Attack on the Same Phase of Combat.
A Monk runs along the wall of a crowded hall (roll Acrobatics) to bypass guards & attacks an enemy with a crossbow (roll to hit). While other classes could do that it might take them two rounds, as the skill use uses up their combat/standard action.
A Monk makes an Acrobatic leap from a wall (that he reached in an earlier round) to a swinging rope (roll Acrobatics) & uses the momentum to super kick an enemy in the face (roll to hit).
As a Monk gains more attacks per round, simply increase the # of free skill uses per action/attack he gets.
4) Monks that save against an effect should take no damage.
Could write more, but I have to get ready for my game. Maybe more later.