I am looking at the Linux benchmarks because that is what I use. I count 11-4 in favor of Chrome and/or V8 with one that’s a tie. For the record I use LibreWolf which is based on Firefox, but it is definitely noticeably slower in my experience.
This is somewhat beside the point but I'd argue there's not even a reason to use Firefox on Windows so those benchmarks are irrelevant entirely. If you're not willing to move away from Windows (a near-monopoly that collects your data) what is the point of moving away from Chrome (a near-monopoly that collects your data). It's extremely half-assed.
Wait, but the three games you listed all work great on Linux. I'm confused. I am a few hours into BG3, I play LoL a few times a week, and I know WoW works because I played a ton of Hearthstone and Overwatch a few years back and those were some of the first games working well with DXVK. So I know Battle.net games usually work great.