After the last thread's resoundingly one-sided result, we move on to our next face-off; which do you consider the more successful system out of the original Xbox and the Xbox One, and why?

Note that this is not the same thing as "which did you like more/think is better", like you can prefer one but think the other was more successful.

OG Xbox was the begining of a new brand that established itself as a major player. Xbox One is the console that told everyone to not give a shit about Xbox anymore. TV TV TV TV TV SPORTS SPORTS! We have a product for people can't connect online it's called Xbox 360. Xbox died right there.

Xbox OG, Microsoft was super aggressive and worked really hard to get 3rd party exclusives on the system. Microsoft also handled really well Halo, Fable and Forza, to try and compete against Sony.

Xbox One, imo is by far the weakest Xbox console, they drifted away from everything that once made them a powerhouse, Xbox series tried to make up a lot of the mistakes Xbox One had made, but in the end ended up continuing the downward spiral.

OG Xbox, the One signaled the beginning downfall of the brand that the Series has continued (and possibly completed). Xbox One S was the first Xbox I ever owned, I bought it mostly to use as a 4K blu-ray player, and it was decent (I have a dedicated blu-ray player now though). 

The controllers are pretty good, and they have genuinely amazing battery-life, I used mine on the PC for some time. During the One era, MS started turning their attention back to PC-gaming again, this was great for me as a primarily PC-gamer, but it did somewhat diminish the attraction of buying and owning an actual Xbox. Of course, this "broadening" of the brand via the One ecosystem and Gamepass has come into full play with the Series, and has taken its toll (heavily). Gamepass has turned out to be a blight on the brand, in my opinion, and has whipped up a highly undesirable model that others have since copied - in the long run this has caused issues for gamers and developers alike. The One was certainly more successful than the Series, but I see it as an overall loss to the OG Xbox, for the same reason the Series loses to it; opposite ends of a spectrum, where one was ambitious and positive, and the other defeatist and dark. 

On a personal note, the Xbox One was part of the most boring generation of consoles I ever experienced. Along with the PS4, it created a market so steeped in sameness and complacency that it completely killed my interest in the console market overall, this has since lead into the very first generation where I don't own a single piece of console hardware for the current generation. 

Same, after the "meh" xbox one, I got a series s, but sold it after a year of owning it, after that went 100% steam.

This.

Xbox One is where MS lost their identity.  The 360 had great Halo support, Gears, Kameo, etc.  One is where I lost interest in Xbox.

This is more or less the other thread but a bit different.
OG Xbox did a lot for the brand and led to Xbox 360 while Xbox One nearly killed the brand (namely the reveal and even as late as 2016).
Xbox One brought in more revenue and surely profit.
Xbox and Xbox 360 were more successful to the brand than the later Xbox consoles.

Still OG Xbox, for essentially the same reasons it destroyed Xbox Series. OG Xbox built and brand. Xbox One came close to ruining it. But credit where credit is due, Xbox One was more a mixed situation compared to Xbox Series. While the built up to the launch was a disaster, the worst in history, with the dumbest, most anti-consumer shit I have ever seen, they did a lot to fix the wrongs. The hardware was overall good, it did have a handful of solid exclusives, they made it backwards compatible with first the Xbox 360, then the OG Xbox. They also added a 4K Blu-ray player to later models. Xbox One X was genuinely a solid upgrade, much more so than the PS4 pro. For better or worse they launched Game Pass, which at least at the time was a decent deal.
The biggest mistake I think (post launch) was deciding to put everything on PC, you need exclusives to keep the brand alive, and even looking at console exclusives, it was just a weak platform compared to the competition. Still 58 million units sold is respectable, and indeed much more than the OG Xbox.