For it objectively speaking. Looking at other acquisitions the regulators have allowed, and comparing it to the Xbox-Activision deal, there is just no sound reason to block it. It gives Xbox a much smaller gaming marketshare than some of these other acquisitions that have gone through, such as Disney-Fox and Penguin-Random House. On top of that, the majority of employees at both companies support it from what I've heard, and the largest union in the US, AFL-CIO, supports it. Has been approved by 3 regulators so far with no concessions required. FTC's case seems to largely be built on false premise. Xbox seems to plan to keep their largest franchises multiplat the remainder of this generation and probably at least part of next gen, like CoD, Overwatch, and Diablo, so at least for the foreseeable future the only exclusives they may get out of it are going to be in smaller franchises like Crash, Spyro, and Tony Hawk, series which won't have a significant impact on Xbox hardware sales most likely.
Subjectively though, I'm more neutral. I don't personally care that much about ABK's games, there are other publishers I would have much rather seen them acquire, such as Sega. A part of me hopes it gets blocked so that Xbox can focus on other, smaller publishers that will be easier to get past regulators and more independent studio acquisitions. I also fear that if the ABK deal does go through, regulators will greatly limit how much else they can acquire afterward, so if it's a choice between only ABK, or no ABK but a smaller publisher like Sega and several more lone studios getting acquired, I will take the latter scenario for sure, as it will put more games I personally play onto Xbox and Gamepass.