For me, it was Brooks in DS9's "Emissary." That sequence aboard the doomed Saratoga
when the Bolian security chief pulled Sisko away from his dead wife and his cry of anguish was something I'll never forget.
Later on, when Sisko finally met Picard, I genuinely thought Sisko was going to strangle him. That look of barely contained anger in Sisko's demeanor and voice, yeah, that was another good moment for Brooks, IMO.