I tried making a mercenary recently after normally picking Tech Specialist, but I didn't really do too well.
So I thought we could discuss our picks for class perks and why we chose them.
My tech specialist has the optional class perks of:
Shield Booster
Volley
Deflector Regeneration
Gravadic Disruptor
Gun Tweaks
Weapon Hack
Second Shot
Shield booster as it scales with player level, giving massive shield bonuses that make the difference in fights, unlike drones, which fail to do more than twenty damage at all levels and take up the accessory slot, which could otherwise be used for massively helpful items like the Lightning Duster and the Light Jetpack, which reduce electrical damage by 50% and increase evasion by 10 respectively.
Volley as it stacks with Second Shot, allowing for three shots total, at a potential 300% damage increase, double the increase of overcharge's 150%.
Deflector Regeneration as it allows for more shield health recovered overall.
Gravadic Disruptor as it deals unresistable damage, as opposed to burning damage. Tech specialists will find themselves using, almost exclusively, energy weapons, the majority of which will deal at least some burning damage, leaving you vulnerable to enemies that resist burning. Unresistable damage is also helpful against enemies that rely on very high resistances against every weapon in the game. Namely Amara Faell.
Gun Tweaks I chose over Weapon Tweaks as tech specialists will always rely on guns with the way their perks are set up. The boost to melee weapons would be helpful in the situation that guns are useless, but those are so few and far between (There are literally only two, the dollmaker, which can be dealt with through EMP spam, and the cuntsnake, which can be one-hit by anyone over level 4) that the skill is dwarfed in usefulness by the boost to energy gun damage.
Weapon Hack and Shield Hack are perhaps the two most useless perks in the game. The damage done by shield hack can
easily be doubled at higher levels, and cannot continue to damage physical health if the target shield is destroyed. You are better off just shooting them. Weapon hack is only useful in extremely limited situations, but it
is useful, so it is what I picked.
Second Shot is a no-brainer, a constant chance for double the damage per turn, stacked with all of the other perks your gun has received.