Original Xbox

1. Jet Set Radio Future

2. Panzer Dragoon Orta

3.  Otogi II

-Honorable Mention is Metal Wolf Chaos. It would be here but I only played it on PS4.

Xbox 360

1. Gears of War 3

2. Raiden IV

3. Armored Core For Anser

-Honorable Mention. Blue Dragon. Underrated RPG.

Xbox One

1. Gears of War 4

2. Sunset Overdrive

3. Killer Instinct

-Honorable mention. Rare Replay.

Xbox Series S/X

1. Hi Fi Rush

2.Ninja Gaiden II Black

3. Space Marine II

-Honorable Mention. If this were a top 10 I'd put a few more in like Ninja Gaiden 4. Daemon X Machina Titanic Scion. Turbo Overkill. Lollipop Chainsaw Repop. Visions of Mana. Metal Eden. Earthion.

Later will do a PlayStation. Maybe Nintendo but to many more consoles. Harder to do.

OG Xbox: 

1. Ninja Gaiden Black
2. Halo 2
3. MechAssault

Xbox 360

1. GOW
2. GOW2
3. Halo Reach

OG Xbox:

1) Jet Set Radio Future
2) Halo: Combat Evolved
3) Star Wars: Knights of the Old Republic

Harder list than anticipated since I love the likes of Ninja Gaiden Black, Jade Empire, Panzer Dragoon Orta, and Project Gotham Racing 2


Xbox 360:

1) Gears of War 2
2) Halo 3
3) Left 4 Dead 2

Honorable mentions to Ace Combat 6, Mass Effect 2, Ninja Gaiden 2, Fable 2, and Viva Piñata

Xbox One:

1) Sunset Overdrive
2) Titanfall
3) Killer Instinct

Honorable mention: Ryse: Son of Rome (repetitive combat, but was quite the technical showcase)

Xbox 1: Halo, Halo 2, Fable 1.

Xbox 2: Halo 3, Halo Reach, Gears 1.

Xbox 3: ?

Xbox 4: ??

Counting only exclusives and first-party games?

Xbox: Halo CE, Halo 2, DOA3
X360: Halo 3, ODST, Reach
XBO: Ori and the Blind Forest, Ori and the Will of the Wisps, Gears 5
XBS: Halo Infinite, Doom the Dark Ages (don't have a third to add; I still have a huge backlog right now and there's a lot of other games I want to play at some point)

xbox: halo 2, indiana jones and the emperor's tomb, 50 cent bulletproof
x360: gears of war, bioshock, eternal sonata
x1: i think all ive played is ryse and halo 5
i havent even touched a single xsx game. lol

Xbox

1. Halo: Combat Evolved
2. Ninja Gaiden Black
3. Fable

Xbox 360

1. Halo 3
2. Gears of War 2
3. Fable 2

Xbox One

1. Gears 5
2. Sunset Overdrive
3. Quantum Break

Xbox Series X|S (In reality this is PC for me, so sticking with 1st-party Xbox games for this)

1. Doom: The Dark Ages
2. Indiana Jones and the Great Circle
3. Halo Infinite

OG Xbox:
* Halo: CE.
* Halo 2.
* Fable: The Lost Chapters.

Xbox 360:
* Halo 3.
* Gears of War 2.
* Fable 2.

Xbox One:
* Gears of War 5.
* Sunset Overdrive.
* Quantum Break.

Xbox Series:
* Halo Infinite.
* Indiana Jones and the great circle.
* Baldurs Gate 3.

Original Xbox and Xbox 360 were such banging platforms... To narrow the best games down to 3 is doing a disservice... Where-as the Xbox Series and Xbox One it's super difficult to chose 3 good games, let alone exclusive games.

X360:
-Mass Effect 2
-Mass Effect
-Bioshock

This would be really close to my list as well. It might be exactly the same as mine, actually.