headshot got nerfed quite a bit in this version, but what i do is more or less:
son of a gun 1/2 -> headshot
or
sustained fire 1/2 -> overkill
if i'm doing an auto build i'll usually take juggler here, and then go for whizkid 1/2 to tinkerer, whereas pistols i'll just go straight to tinkerer. tinkerer is an awesome trait which allows you squeeze an extra medkit out of every health terminal, as well as a power mod and some change out of every item terminal
after tinkerer i'll go up to remote hack as i think its worth it to carry a stack of multitools for the chance to remove a cri bot from the playing field, especially if its at full health and can be used to attack other stuff. plus the ability to hack turrets via terminal and the more or less free of charge (as well as the drones) is incredibly useful too
if i'm doing auto build, before i get to io i'll take gun hoarder to free up an extra slot for a plasma rifle and usually take shottyman before the end if i don't find a shotgun with autoloader trait. for autobuilds, strong shotguns are essential imo for staving off strong melee enemies, and as a result i'll usually take a shotgun utility over rifle utilities during an auto build. it might sound counter intuitive, but souped up plasma gun (nevermind adv chainguns or whatever) are more than enough to get the job done at range, but if strong reavers are in your face, you'll want to take them down asap with something like the jackhammer, adv double barrel, heavily modded plasma shotgun etc
for weapons if i'm doing a pistol build i'll balance out the early game with revolver and 9mm guns based on the perks i get out of adv weapons. io and on i try to have one that takes 44 ammo, one that takes 9mm ammo and one that takes cell
for auto build, i'll balance slots between a short range slot (shotguns), medium range guns (9mm auto to 7.62 auto to chaingun usually), and long range guns (hunter rifle to rocket launcher), and then when i get to io switch between chaingun and plasma rifle for medium range based on what ammo is available on the level
since adv chainguns, rocket launchers and plasma rifles are quite rare compared to other types of guns, i usually just start throwing mods into the standard versions of these weapons. with pistols is usually worth waiting for an adv to overly mod stuff, but with the dismantle action you can cycle one mod through guns without penalty