Here’s what I’m noticing in nearing a week of using the XS Max and having previously used the Note9 for a month: Overall, the Note has the better battery life in my use-case, but not by much, and not enough to really make a difference for me. The iPhone has always excelled at standby time, where the Note, and any Android for that matter drain quicker during standby. I do think the Note delivers better longevity during actual screen-on use though.
Overall, I can squeeze out 5-7 hours of SOT with the XS Max, and 6-8 hours of SOT with the Note, sometimes even pushing that top number closer to 9 hours. That’s just specific to my use-case though, and as another member pointed out previously, each side could be calculating SOT differently somehow. Everyone‘s usage patterns are different as well.
I think both would last you comfortably through a single day, but the Note is more likely going to push you further into the second day. For me, I recharge nightly when going to bed anyway, so either will give me enough longevity for my needs.