So, I ended up falling asleep super early last night without playing either game. But, I woke up at 4:30am today, a few hours before the rest of the family, and started on Gears. I'm into the beginning of Act II. So far, I'm very favorably impressed.
I do feel like there's a lot of story context that I would benefit from if I played the older games first. But, I just ain't interested in going back to play games from a decade ago.