I've always said that Season 2 is probably DS9's best season or at least its most under appreciated one.
It's almost all good to great episodes.
But, more than that, it was DS9 at its most daring, most diverse. While later seasons were dominated by a few major storytelling arcs, in DS9, the writers weren't afraid to get weird. The episodes run a much wider spectrum of storytelling and subject matters.
To be fair, there are certainly some duds, like Melora, Second Sight and Rivals.
But there are outstanding episodes like "Whispers", "Necessary Evil", "The Maquis". There are underappreciated gems like "Rules of Acquisition", which still cracks me up and is arguably the best of the Nagus/Ferengi-centric episodes in the entire series. Even a straightforward episode like "Armageddon Game" is actually quite good and plants the seeds of the Bashir/O'Brien friendship. The Jem' Hadar were never scarier than in the episode that bears their name and "Sanctuary" was one of the few times any of the modern series did TOS-style social commentary well.
I even dug "The Collaborator" and the Circle Trilogy, even though I can't say that I really missed the Bajoran-centric storylines when they were ultimately put to bed.
Basically, Season 2 soars because of its variety. The episode explores many corners of the DS9/Trek universe. There's comedy, political thrillers, social commentary, sci-fi, romance, drama, etc. It's the perfect stew and really showed DS9 coming into its own.