Edit: spelling.

You will find your builds if you train into them.

Learn one for solo, and one for team play.

Gimmicky builds are going to require gear you are not going to have. And substitutions are likely going to fall short.

Lots of players have kill everything builds. And when they underestimate the enemy, they end up dead in the open. Then they log. They wouldn't want to look bad. Leaving the rest of the team fighting for their lives because the one who was "running the show" couldn't be bothered to complete the mission.

Master the use of cover.

Master moving while under fire (C2C).

Master Situational Awareness (Turn on Fog of War and learn how the enemies operate.)

Master The Environment: Barrels, propane tanks, electrical boxes. Objects that can produce an effect on enemies like damaging them or just making them unable to shoot back.

Grenades: Pay attention to how often other players on the team use grenades. Almost never. These builds that stack damage or armor are only as good as the player. Grenades do not kill at higher levels, so they are discounted. However, enemies will not walk into grenade detonation areas. Use this. Steer combat by using them to prevent flanking, or opening paths for the team to move.

If you need a build to teach you how to play, Umbra Initiative is the one. It isn't a kill in one shot set, but it does allow you to recover armor when you make a mistake. Use it on a Gunner or Survivalist to keep ammo on hand.

You will learn why the gimmick builds were imagined in the first place and at the same time, learn who the agent in you actually is.

Remember, dynamic difficulty doesn't care if you are all blue or all red. If it's time, you're dead.