I have been playing a long time and a recent post that skill build sets were being run by idiots wasting their time as Striker was SO GOOD got up my nose.
I have an abundance of CS armour pieces completed, though I deleted a completed set of Final Measure and D3FNC before reading an article about skill building using as Nomad set as the base. My agent is 4 piece CS, GS kneepad, inventive back pack (15% skill power addition).
With all Nomad pieces, 5 CS, 1 GS, it runs 350K, 5 CS, steal 1 piece from main agent, 360K, but you get the 6 piece CS bonus.

The Nomad reference was what caught my eye, but then saw other articles on using Tactician Authority and regrettably Final Measure and D3FNC.

Now is a great time to try one as Electronic modules are on sale but ending very soon in DZ 34 West for $21,362 DZ funds for a 259 Electronics module with 3,303 skill power as a minor addition. Less spec mods are available through the BOO (general funds) and Camp Clinton (Phoenix Dollars) look up Rubenalamina on google, search for the division Vendor reset. Lesser spec mods will still make a very good build, depending on what funds you have available.

Recalibrate any of the CS sets to most or all Electronic base with skill power where it is available, look up skill build guides on YouTube, there was really good one based on Tactician Authority but most others are suitable.

Electronic base with skill power where available, but other options such as Skill Haste but if you can't get them, Enemy Armour Damage, Ammo capacity.

On items limited for choices such as gloves, select an option such as 12% damage on your primary weapon, SMG, AR.

If yopu don't get all options as they have been calibrated / optimised already, no big problem your skill power will be down a bit but many find the FP / Stamina levels too low so you may want to swap things around to suit how you play.

Fully skill powered builds are being used to run Legendary missions solo, search for those on youtube, interesting watch.

My Nomad hybrid build is 390 K skill power,with it can take out a purple mob if perfectly placed, reds are vaporized, takes a lot off yellows, but more than good enough to handle LZ Boss runs and even the DZ lower levels.
It takes about 10 seconds for the sticky bomb to reset, you have moderate firepower to kill the NPC's, you will be squishy but it is manageable but great fun.

If you want more killing power and a bit more risk, run the seeker mine also, for me swapping out the booster shot, but you hit the mob with the sticky, shoot any survivors and in 4-5 seconds and any NPC's remain launch the seeker mine, shoot the survivors, shortly after that the sticky bomb is available again.

The main issue you will face in survivability is mainly for me only in the DZ where killing 1 mob, signals many more to rush in, but good use of cover, sometimes retreat to a better area, use of grenades, make it manageable.

Play the Division the way you want to, not just in cattle cookie class armour, though it is good for a reason, it works brilliantly, but other sets give a different and great fun experience.
Nomad has resilience and a healing factor, Dead Eye has incredible hitting power combined with really good sticky bombs and seeker mines, Firecrest has the bonus fire turrets and extra incendiary grenades, BUT NOT A SOURCE OF SUPPLY, just try it on any set and see if you like it.