I haven't seen ep7 yet, and I wouldn't make a ranking quite yet, either, but so far the one episode that gave me a better impression than the rest is ep5: "Choose your Pain". Less clichéd (still some clichés), better dialogue (overall), less pew pew (still a lot of pew pew), ... but Lethe brought the clichés and hackneyed writing back in force.
Although "Choose your Pain" isn't much good on an ethical standpoint. We start the series off with a war crime (boobytrapping a corpse), and now we leave civilians (immoral civilians, sure, but that's no reason) behind on an enemy ship, to be tortured to death?