Any good Ferengi/Quark Episodes in the first 3 seasons?
I think there are I just can't remember the names...
The House of Quark is great.
Rules of Acquisition is OK. I like
Profit and Loss, mostly because it introduces Cardassian dissidents and because it's a good Garak episode, but it's also fun to see DS9 do
Casablanca with Quark in Bogart's role.

(Though BTW it makes a lot more sense than the real
Casablanca with the "oh she must stay with her husband because he's a resistance leader" nonsense (or what? She's his support system and he'll fall apart without her?)

because Natima is a leader of the dissident movement, rather than a leader's wife.
I'm looking for Romulan Episodes as well...
.
I don't think there are any in the first 3 seasons apart from Improbable Cause/The Die Is Cast, and The Search.
Well, its only my opinion, but for me the best and most important eps of the first 3 seasons would be:
If I was going to recommend someone a rewatch, I'd definitely add more episodes to that list.
Season 1
Emissary
Past Prologue (first Garak ep)
Captive Pursuit
Vortex
Duet (generally considered a classic)
In The Hands of The Prophets (first Winn ep)
That's pretty much it, though Battle Lines is sorta important because of what happens with Kai Opaka.
Season 2
The Homecoming/Circle/Siege
Cardassians
Necessary Evil (generally considered a classic)
The Maquis I & II
The Wire
The Jem'Hadar
+
The Alternate (it's not great, but it introduces Dr Mora who'll return in season 5, and we learn more about Odo's past)
Whispers (great episode)
Profit and Loss (we learn more about Cardassian society, with the introduction of the dissidents, and it's a good Garak episodes)
Blood Oath (brings back the 3 Klingons from TOS, and Kor will return later in the series)
Crossover (the only good DS9 MU episode)
The Collaborator (Winn becomes kai)
Tribunal (it's not really that important, but it's a great piece of black comedy about a totalitarian judicial system)
Season 2 is very underrated, IMO.
Season 3
The Search I&II
Second Skin
Defiant
Past Tense I&II
Improbable Cause/The Die Is Cast (generally considered a classic)
Explorers
The Adversary (not really a cliff-hanger, no, but pretty ominous and foreboding)
+
The House of Quark (great episode

And yes, Grilka also comes back in season 5)
Equilibrium (we learn more about the Trill, and Joran comes back a couple of times)
Civil Defense (simply because it's fun, especially with Dukat/Garak animosity)
Life Support (Bajor and Cardassia sign a peace treaty, and Bareil dies)
Destiny (more Cardassians? Always a good thing. And interacting in a fun way with O'Brien? Even better)
Shakaar (involves important political changes on Bajor and introduces a recurring character)
Facets (a good Dax episode - and one where we finally get to meet all of the former hosts)
maybe also
Family Business (no, I don't think it's good, but it is important for future Ferengi storylines)
Or you could just watch the entire season, just skipping
Meridian and
Fascination. Yes, I know that some people like
Fascination, but I absolutely loathe and despise it. And it's not even all that funny.