Given how limited our look into the other timeline we can't say for sure it was significantly better. We can't even be sure that the Dominion War didn't happen. The Federation and Dominion could have gone to war multiple times over the 50+ year period, but we never heard about it because to Jake it didn't matter, nothing outside his obsession with freeing his father matter. The Federation and Klingons could have had multiple devastating wars with each other, hell Leyton might have become Emperor of Earth!
At most we can say it is "better" in the sense that Jadzia got to grow old and not be murdered in her 30s.