Iv been playing mainly against a friend who plays Tau, also against my brother playing Dark Eldar, i need a single army that can stand up against both very different armies.

Heres what iv got so far:
Autarch w/jump generator, mandiblasters, power weapon and fusion gun. 125

5x Scorpions inc exarch w/chainsabres. 97

5x Banshees inc exacrh w/mirrorswords. 102

5x Dire avengers inc exarch w/bladestorm. 87

5x Pathfinders. 120

Heavy support
Falcon w/Starcannon, Shuriken cannon, Vectored engines, Holofields and Spirit stones. 215

I cant decide wether i should mount my scorps in the falcon or get shaddowstrike and infiltrate to let my banshees go in the falcon.

I figure with the jump generator my autarch should be able to stay out of sight if he cant assault anyone and with 12" move d6 fleet and 6" assault he can make cc prety easily (i hope)

My friend with Tau normally fields about 6 or so suits, 2 squads of 2 crisis suits, a broadside suit with t-link rail gun and his hq, cant remeber what but he has a 2+sv i think and feel no pain, best way to go about him is with power weapons

My brother playing Dark Eldar fields an army which i dont know much about, big troop squads that tend to sit back for a few turn and fire dark lances, witches? on a transport, if i can get a shot at it early enough the transport will go down easily, armour 10 10 10, but it can cause hurt with a dark lance if i dont deal to it early. his hq is a humunculus? on a jetbike, 2+ sv as i remember, also he has some warp beasts and beast master with agoniser, they dont normally cause me too much trouble really, only annoying that they have 12" assault. its quite possible im wrong about his army, im not fully up to play with his army/rules.

any suggestions would be apreciated