To be honest, effects wise they both hold up today. Sure it wouldn't compare to the Kelvin movies or even disco in terms of visuals, but we're talking about 2 series that are more than 20 years old and I can still happily watch them both without the effects looking to jarringly outdated.
Of the two though, DS9's sets were alot richer. The promenade was alive, the crew quarters detailed, and ops full of hubbub. Compare that to the sterile nature of Voyagers sets and well...
And the battle sequences in Ds9 were far more ambitious too. The only real gripe I have about them is the obvious copying and pasting of some ship models in scenes. But you have to make some allowances considering this was new ground for TV at the time.
In fact the total-CGI nature of Voyager really meant they had no excuse not to show wear and tear on the ship as the series progressed because they didn't need to keep altering an actual physical model.