So, I miss these heinous monsters from 3rd ed 40K. I'll be the first to admit that, in the game, they weren't always the most useful unit, with no Get Back Up, and a bit of a cost, but they were cool, they COULD work, and they were a model I rather liked.
I'm working on a small, secondary-seeming Necron Dynasty, led by one Phaeron Akhenatekh. This is the slumbering dynasty that my RT character, Korvallus, stumbled upon about a century ago, and picked up his weird cargo. In addition to her, this dynasty is focusing on creating Pariahs. In not-standard fashion, the Necrons have taken people captive, and are trying to breed them in intensified chronofields, trying to form a more frequent occurrence of the Pariah gene; where they got the initial source is anyone's guess, whether they captured a Culexis Assassin, or have always had it, but they want to make a stock of Blanks, if you will, to convert into Pariah Necrons.
So, the point here is, were you to decide to tackle using Pariahs in THIS game generation, where they might not still exist, but they could be a project of a single Dynasty, maybe, would you favor taking say, an Immortal stat block, and adding the Null template to it, or build a potent Blank warrior, like a Culexis, and add Necron bits to it, giving it the Machine trait, and deny it the other Necron advantages (this is more what the TT game did). Either is possible now that their fluff is in limbo, but what seems better? Thanks.