The truth here is, both bracelets are overall the best they've ever been from a comfort perspective, and both also need improvements.
Sub owners are finally happy with their bracelet. If you go back to the mid 2000's or so, Omega SMP had a far superior bracelet. The Rolex bracelet was a rattle-trap that felt cheap, had an ugly clasp, and hollow endlinks. In comparison, the Omega SMP had a much more solid clasp, nicer links (although not screwed links). Ever since Rolex upgraded the sub bracelet and added glide-lock, Rolex owners have been celebrating.
However the latest sub 41mm, the clasp is now absolutely massive and while the glidelock mechanism has probably been made more robust, the new size of the clasp is absurd, and in my opinion a big downgrade.
Similarly, the Omega SMP bracelet while super comfortable, definitely has a polarizing look (referencing that 90s bond seamaster look), and without the taper it is a chunky monkey that doesn't really have a modern look (as most new watch releases have tapered bracelets with a bit of vintage vibe, including the new speedies).
At this point, both bracelets need to go on a diet, the sub with a smaller clasp and the smp with a taper. The trick will be if someone can do a no-tool-required infinite microadjust/pushbutton micro adjust while keeping a small clasp. I think omega specifically didn't add this functionality to the new speedmaster in order to keep the clasp a manageable size.
-Freq