Easily 360. Great console.

Granted I've only tried the OG and 360.. the Xbox 360.

Mass Effect
Bioshock
Lost Odyssey
Alan Wake
Call of Duty 4: Modern Warfare

Xbox 360 was my favorite followed by the original Xbox. Even though I'm enjoying my Series X a lot, not enough has released to make it my favorite. We'll see how things look at the end of this gen. The Xbox One didn't have enough big exclusives.
Top 5 360 games would be:
Halo 3
Gears of War 3
Mass Effect 2
Call of Duty 4
Fable 2

OG Xbox due to Halo.

Tough to narrow down to just 5 but here goes.

1. Halo: CE
2. Ninja Gaiden Black
3. Halo 2
4. Splinter Cell: Chaos Theory
5. Mech Assault

The OG Xbox was my favorite because not only did you have some great RPG's but of course you had Halo. So many Halo LAN parties......good times! Not many remember just how many exclusives the original Xbox had.

My top 5 Xbox games were

1) Halo 2
2) Jet Set Radio Future
3) Star Wars: KOTOR
4) Project Gotham Racing 2
5) The Elder Scrolls III: Morrowind

5 honorable mentions

Halo: Combat Evolved
Fusion Frenzy
Star Wars: KOTOR II
Fable
Amped 2

Xbox 360! Wooot! I waited for like 2.5 years after launch for better revision since the consoles had the plagues of RROD, although it had great first and third party games. (in no order for games)

-Gears of War
-Gears of War 2
-Alan Wake
-Halo 3
-Fallout 3
-Oblivion
-Batman Arkham Asylum
-Mass Effect
-Devil May Cry 4
-Resident Evil 5
-Ninja Gaiden II
-Bayonetta
-Prey
-Condemned
-Condemned 2
-FEAR 2
-Brutal Legend
-Guitar Hero III
-Spider-Man Shattered Dimension
-Prototype
-Dead Space
-Dead Space 2
-Virtua Fighter 5
-Sonic's Ultimate Genesis Collection
-Metal Gear Rising
-Castlevania Lords of Shadow
-Silent Hill Homecoming
-Singularity
-Darksiders
-Dead Rising
-Lost Planet
-Bioshock
-Grand Theft Auto IV
-Bully Scholarship Edition
-Red Dead Redemption Undead Nightmares
-The Darkness
-Bulletstorm
-Left 4 Dead
-Left 4 Dead 2
-Deus Ex Human Revolution
-Alice Madness Returns

Followup the OG Xbox! Damn, back then i couldn't able to have a new rig to play game properly, my PC was junky as heck. (in no order again)

-Halo 2
-Doom 3
-Half-Life 2
-Serious Sam
-Serious Sam 2
-Painkiller
-Mortal Kombat Deception
-Hitman 2
-Legacy of Kain: Defiance
-Tomb Raider Legend
-Timesplitter 2
-Max Payne
-Max Payne 2
-Sonic Heroes
-Shadow the Hedgehog
-Ninja Gaiden Black
-Spider-Man 2
-Spawn Armageddon
-Batman Vengeance
-Morrowind
-Conker's Live and Reloaded
-Star Wars Jedi Knight: Jedi Academy
-Stars Wars Jedi Knight II: Jedi Outcast
-Bloodrayne

XBox 360

1. PGR 3 and 4
2. Mass Effect
3. Alan Wake
4. Dead Rising
5. Kameo

Of course Halo, Gears, Forza were great as well on 360.

OG Xbox had a ton of incredibly unique and original games I adored, and nostalgia has me leaning that way, but really I don’t think I can answer anything else besides the Xbox 360. There was not a game console I ever used more, and the amount of awesome games from that generation I still don’t think has been topped

I gotta go with the Xbox None (never had an Xbox)

OG Xbox.
- Halo.
- Halo 2.
- Fable: The Lost Chapters.
- KOTOR.
- Elder Scrolls: Morrowind.
- Jade Empire.
- Blinx.
- Jet Set.