Ok yes people want an op demi company that dosent follow out fluff. However. The archangels demi company offers a very fluffy alternative which is near on the main when assisted by an Inquisitor.
May I suggest running 3 squads of vanguard vets, one termi squad, and one sternguard squad for your demi company, some grav cannon or las cannon devs for your aux, and 4 sanguinary priests for your vanguard and sternguard squads. Add in 1 or 2 inquisitors with 3 servo skulls each and you have an interesting list.
Let's talk about it shall we? The archangels demi company can deep strike turn 1. Rerolls failed reserve rolls, and scatter a d6 less. Now let's add in the servo skulls from the Inquisitor that reduce the scatter dice by 1d6 if the first model of a unit is within 12 inches of it. They also stop infiltrate and scouting units from gaining much ground.
I suggest 1 line of servo skulls as close as possible to the opponent to stop scout moves, while having a second line of skulls for your angels to drop in and take a spot on the board without error(barring terrain instances that could cause mishaps).
As always feedback is welcome.