Power Management is the best crafting feat imo if you have elctronics. 35% more capacity on energy shields is basically 35% more health.
Gun Nut is pretty weak, not worth the INT investment on it's own, but if you already have 7 INT to get other feats you might as well take it on builds that are not too feat-hungry.
Weaponsmith is good I guess.
Armor Sloping is good if you want to use anything with metal plates and keep your armor penalty as low as possible.
Ballistics is too weak to mean anything, a waste of feat.
Clothier/Skinner are a flat increase in cloth/leather quality and that's always good.
Disassemble is very convenient. I can't imagine looking for new mods every time I find a marginally better frame.