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