Too much pseudo-mysticism, not enough pseudo-science... DS9 wasn't Trekish enough for me to like it much, but I still ended up watching... I even prefered the very average Enterprise and Discovery more than DS9, so TOS, TNG, and Voyager easily blew it out of the water (IMO).
If you want to watch a Space Station-based show mostly done right, I'd recommend Babylon 5. It ran around the same time as DS9 (don't feel like looking up which one came first), and it kicked its ass (IMO).
See the differences are actually what made me love it so much. They took Trek and said "what happens when shit hits the fan?"
Granted, without being drawn in by the awesomeness that was TNG, DS9 wouldn't have held the same appeal.
Also, I thought DS9 had some of the best characters in the franchise - Garak, Quark, Garak, Odo, and of course Garak. Sisko was a great captain - a tactical genius and idealist, but unhinged enough to be human.
Honestly I never got much into TOS other than a few episodes and the movies. I grew up on TNG. I also really like Voyager. Enterprise was decent at the beginning and fun at the end, but crap in the middle. I can't even bring myself to watch Discovery at this point....
I never got around to watching Babylon 5, even though I meant to. I will say if it blows DS9 out of the water, it'd have to be my favourite show of all time.