She has her reasons, obviously, but she's angry at:
- Dukat. Ok, Dukat is a terrible person (quite frankly, he's a monster) and completely deserves it.
- Quark. Ok, he's a crook.
- The provisional government. Ok, the provisional government is incompetent and corrupt to some extent... or, at least, she perceives it that way. Whilst being part of the administration (as liaison officer to DS9).
- The Federation. Ok, she perceives the Federation as new invaders.
- Sisko, before learning he's space jeebus. Ok, he represents the Federation.
- The station computers.
- I forget who else. Long time I haven't seen DS9 (at least in its entirety). It just seems that in every scene she's angry and yelling. I found it grating.
Sure, she has her reasons (some very valid, some less so), but she always throws a tantrum whenever something doesn't go her way. IRL, people like that, you always feel like you have to walk on eggshells around and it's exhausting.
(aside: Quark absolutely is weaker than her. She's second in command of the station, he has no authority. Physically, she could very easily overpower him.)
Yeah, Dukat was a monster in general and the symbol and chief architect of the occupation in particular. If Kira wasn't angry at him, she ought to be up for sainthood.
Quark, not only is he a small-time crook but the way he makes his living is getting people to drink too much and gamble. Not great traits as seen by a spiritual person.
The provisional government WAS a bunch of squabbling opportunists who hated each other almost as much as the Cardassians. Kira didn't exactly hate them, but was very frusterated with them and some anger is certainly justified.
The Federation. She's barely experienced the Federation before the series opened. How is she going to know that the Federation is almost always the good guys, who don't interfere with weaker civilizations?
Sisko. It's a Bajoran station, so why the heck isn't a Bajoran (like me for example!) in command? Why isn't HE first officer?
The station computers ARE evil especially at first before Miles went all David Bowman on them.
Then add that she spent from age 13 or so until however old she was in season 1 (late 20s?) fighting, hiding in the woods, killing Cardassians and collaborating Bajorans. That's a heck of a way to grow up, and in real life she'd probably be way more screwed up than they showed.
Kira calmed down pretty quickly after the first 3-4 episodes of season 1.