Ron over at FTW has asked the contributors to work on a collaborative post concerning the units we consider our, "must-haves".
My must-have unit is the second HQ choice.
Even in a 500 point list I always try to include two HQs.
Sure, they are not as damaging as the heavies or as flashy as the Elites, but they are solid and vicious in their own right.
Let's face it, the stat block is always better, the armor is always better, and the wounds are always better than your standard troops choice.
For example take the Shas'o XV-8 Commander suit. BS is 5 with the from the word, "go". Acute Senses, Deep Strike, Jet Pack, 4 wounds, a hard-wired drone controller, 4 attacks at initiative 3, and a 3+ armor save come standard. Add in a shield drone and another drone of your choice and you add a +4 invulnerable save and two ablative wounds to the mix.
Basically, your HQ looks something like this; hits on everything but a 1, has 6 wounds, if you take a twin-linked weapon system you will never miss (unless your dice hate you), 12" of move per round, the super-duper insta-kill wounds can be ablated to a shield drone, in short you have a nearly unkillable HQ unit on the board.
The only thing that would make it better is if you had two....
Think about it.