Before we get started a tip for you:
Generally, the best builds in this game use one weapon dedicated to a single target and the other to crowd control.
As for the rest of the gear: Use whatever can complement your weakness so that you would have an all-around great build rather than a one-trick pony. This is so you would have an option for every situation and wouldn't get killed because you dedicated all your arsenal to one specific thing.

I use pretty much the same perks, pickaxe, equipment, and armor upgrades for all builds I have.

• Resupplier
  
• Sweet Tooth
  
• Vampire
  
• Dash
  
• Iron Will

*This is the same for all my Driller builds

*This is the same for all classes

*This is the same for all my Driller builds

*This is the same for all my Driller builds

The best throwable for Driller in my opinion, so I use them in every single Driller build I have.
Good option for single-target elimination, is easy to use, cost-effective, stylish, triggers vampire, and has lots of cool tricks, for example:

• Did you know that you can use impact axes as an easy way to deal with the spider webs in the caves? Just throw an axe at the web and then you can pick the axe up afterwards.
  
• Or you can make your C4 levitate by throwing it and then hitting it with an axe, after which

*This is the same for all classes

This build uses Cryo Cannon for freezing enemies and Wave Cooker for finishing off frozen targets.

A popular strategy amongst DRG players is to freeze enemies and charge at them with one of your melee weapons, however at higher hazard levels it is very risky and axes are too valuable to throw willy-nilly, so as an alternative you can use your Wave Cooker to clear out the frozen pests from a save distance and save your axes for bigger, more valuable targets.

*Weapon paintjobs were applied with the help of No Cosmetic Restrictions mod

This build is similar in playstyle to the previous one.
You set the swarm on fire with your CRSPR and then finish off the bulkier enemies with your Wave Cooker.

This build is very flexible and has tons of options in that you can use both of your weapons for dealing with groups of small targets as well as dealing with tankie enemies.

This build was purely made for dealing with Industrial Sabotage, so this build has every tool in the shed for dealing with everything you can encounter in this particular mission type.

You have your drills for dealing with the turrets and shredders, your charged shots from EPC for dealing with sniper turrets, your regular Cryo Cannon for dealing with swarms, your C4s for damaging all glowing bits of Caretaker at the same time, your Ice Spear for dealing massive amounts of damage to the Caretaker's exposed parts, etc.

This build was made for Elimination missions but can be used in any other mission type.
Both of your weapons are more than capable of dealing massive amounts of damage but when used together they benefit massively from each other.
Use your Sludge Blast from up close (lol), and use Subata to finish off weakened enemies or kill targets at long range.

This build uses Disperser Compound to fight against swarms and Gamma Contamination to weaken and finish off the enemies.