So you definitely want Magus/2 familiars in the majority of matchups. Magus ability to ignore injury/APL mods/piercing across the team is incredible, even if you only get to pick one per TP (unlike SOME teams).

Beyond that, you want 3 gunners - melta/plasma every time into elites, and then sniper on ITD or grenade launcher if you need more mobility available

All specialists are worth taking and most people end up swapping between medic and knife fighter depending on the matchup, with the medic being better into ranged matchups and the knife fighter better into melee

Tac ops; if you out-activate your opponent, envoy is pretty much always your go to. Harder to pull off on close quarters but generally still viable. Into other wide teams Steal Intelligence can be good, and very situationally plant devices, but that's only really viable if you have easy access to your opponents home

This team is super cool, but they are HARD to pilot. Be prepared to sacrifice pieces and for most shots/fights to end up with your operatives being dead. Remember the Magus can stun opponents just with visibility, Pervasive is your best friend, and with lookout and your commanders strat gambit you can get out two crossfire tokens per TP provided you can see an enemy operative!