Currently Online 
I've never played an Xbox Series and never owned an OG Xbox, and I haven't put in 1000 or more hours playing on Xbox consoles, so take my opinion with a grain of salt.
It's between Xbox 360 and Xbox One, the two I own. Xbox One has more games to play overall thanks to its library and 360 backwards compatibiliity. But Xbox One has less exclusives and console exclusives, and a base Xbox One (which I don't have) is weaker by 2013 standards than 360 was in 2005. One X (which I have) makes up for some of that.
360 is a largely plug-in and play device. Not many games require updates to play, and installations are optional minus a few exceptions. One thing that is unfortunate about Xbox 360 is even free-to-play games require an online subscription. Even Xbox One eventually course-corrected on that.
Xbox 360 is a more unique experience as well. Xbox One and Series X/S are quite similar to each other and have some overlap with PC.
Xbox 360, but Xbox One is closer than some think.
Lifetime Sales Predictions
Switch: 161 million (was 73 million, then 96 million, then 113 million, then 125 million, then 144 million, then 151 million, then 156 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 48 million (was 60 million, then 67 million, then 57 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima
