what do you want to do with them?
TBH, it sounds like you're using them for melee as opposed to tank hunting.
i'd go with the plasma and LCs. if used for tank hunting a 5 man unit of Raptors with two melta guns will suffice.
Amid the Weeping and the Woe, Accursed Daemon Thou Remain And Rot; I Know Thee Filthy as Thou Art I Know...