Don't forget to the get kill a raptor while zoomed in with the sniper rifle trophy/achievement
I hated buying the seeker rifle just for that...
That gun was always useless to me... you're never in a secure sniper perch so it and the zoom function don't really make it a good fit for much. :\
Flamethrower was another one that I never really gave a shit about.
Speaking of useless guns -- the two LE weapons make everything else useless, especially once you've beaten the game once and do new game + for the other modes.
Seriously. Oh, I got to the first bench? Give me both those weapons, pop the stasis and acid modifiers on them (non-classic mode) and I never really deviate.
Before I discovered them, I had a line gun with various lower attachments as well as a plasma rifle with the line gun's alt fire from DS2 as the lower tool.
Toward the end of the hardcore run, I changed the contact beam to a canister mine gun. I tried the electrified bolas, which were cool... but I think I got killed a couple times by them. :(
What weapons did you craft that you found to be the best? I seriously got 90% of my kills with the line gun (+stasis or +electric) or shotgun (+acid).