Yes they are very good games, all of them are rts, except Space marine, which is a third person shooter.
Ah yes, but the difference is Vermintide takes place in Warhammer fantasy, while the games i listed take place in the war hammer 40k universe with space ships, and futuristic shit. There are theories that they are really in the same universe but i wont get into that.
Vermintide is a really good game though, and i highly recommend it.
Do you play vanilla or ultimate apocalypse? Because i always though Necrons were kind of weak in Dark Crusade and Soulstorm, but the ultimate apocalypse mod makes them insanely powerful.