Im enjoying my Allied Tau force.
Commander Shadowsun + Warpspiders (I call them ShadowSpiders). Marginally slower than Spiders alone (no Battle Focus/Warp Jump) but Shadowsun's Warlord Trait adds a little extra speed not to mention Stealth/Shrouded and if you have the points, her Drone that gives you the rerolls to hit is always handy.
Alternatively, if you're in a distinctly apocalyptic mood then you can field an Ulthwe strike force and give the farseer carrying the wraithgate the Faolchu's Wing Remnant of Glory. The farseer can then fly across the board and deploy his wraithgate, so your shorter range units can be unleashing their fury by turn two.
Not to mention the fact that the avatar can get stuck in without facing the enemies heavy weapons.