Best Strategies and Ships for the Different Difficulties

I have some questions. The devs and in-game text seem to highly reccomend the flak cannon - however, its' stats, when I've found it, do not seem to outperform the particle cannon.

Likewise, the weapons I pick up from enemies do not seem better than what I can make myself. Often damage stats take an unacceptable hit, in exchange for inadequate increases to stats like range. Is this intended, that enemy weapons are best for scrap to fuel your own construction efforts? I would think that you'd want to feed the loot frenzy, if possible.