Well, for that, let me go ahead and put up a table for the original Battlemaster
The main tweak I would suggest is to drop the extra feats and replace them with extra reactions or bonus actions. And bring Indomitable forward so that people actually use it.
Some of the clumsy wording is there to prevent multi-classing cheese.
Level Proficiency Bonus Bonus Features
1st +2 Fighting Style, Defensive Bonus
2nd +2 Action Surge (1 use), Second Wind
3rd +2 Martial Archetype
4th +2 Ability Score Improvement, Indomitable (1 use)
5th +3 Extra Attack
6th +3 Combat Reflexes (1)
7th +3 Martial Archetype feature
8th +3 Ability Score Improvement
9th +4 Indomitable (2 uses)
10th +4 Martial Archetype feature
11th +4 Extra Attack (2)
12th +4 Ability Score Improvement, Instinct
13th +5 Action Surge (two uses)
14th +5 Combat Reflexes (2)
15th +5 Martial Archetype feature
16th +5 Ability Score Improvement
17th +6 Indomitable (3 uses)
18th +6 Martial Archetype feature
19th +6 Ability Score Improvement
20th +6 Extra Attack (3)
Defensive Bonus: Your base Armour Class can become 10 + Armour + Defensive Bonus. Your Defensive Bonus is the lower of your Proficiency Bonus or your levels in the Fighter class and is limited by armour as your Dex bonus is (e.g. max of +2 with Medium Armour). You may add to your AC with a shield, Fighting Styles, magic, and the like. Your Defensive Bonus may not be used with any type of Unarmoured Defence but may be used when you are out of armour.
Action Surge: starting at 2nd level, you can push yourself beyond your normal limits for a moment. On your turn, you can take one additional action on top of your regular action and a possible bonus action. Your Action Surge lasts for a number of consecutive rounds equal to the lower of your Proficiency Bonus or your levels in the Fighter class. Your Action Surge ends early if you are knocked unconscious. You can also end your Action Surge on your turn as a Bonus Action. You recover all uses after a Short or Long Rest.
Indomitable: Beginning at 4th level you may pass a saving throw you fail (q.v. Legendary Resistance). In addition, if the save is versus a spell which does not ordinarily allow a saving throw the spell has no effect if it does not do damage or does half damage if it does damage. You may use Indomitable once per Short Rest. At 9th level you may use Indomitable twice per Short Rest. At 17th level you may use Indomitable three times per Short Rest. You recover all uses after a Short or Long Rest.
Combat Reflexes: at 6th level you gain an additional Reaction or Bonus Action. At 14th level each round you now have an additional Reaction and Bonus Action. You may change your choice after a Long Rest. The Reaction and Bonus Action must still be activated as per normal.
Instinct: at 12th level your base passive Wisdom (Perception) scores become the better of 10 + Proficiency Bonus or 10 + Wisdom modifier and you may use your Proficiency Bonus instead of your Wisdom modifier when making active Wisdom (Perception) rolls.