Originally Posted by The Irish Commissar
For example tau have battle suits but why not try make something as powerful and tough armor and give them standardised better fire warrior armour.
It is more than the armor that protects him that keeps an Astarte alive. it is his physical and psychological conditioning, his training, the weapon he uses, and the resources at his disposal that all come together to create one of the most effective killingmmachine the 40k galaxy has ever known. The Tau cannot simply recreate that, and unfortuantly the Earth caste has not changed their way of "armoring" their units for quite some time.
As for other races they have all created their own verzion of "Ultimate Soldier" breeds
The Orks naturally develop Nobz, Mega Nobz, Bionik Warrioz, and Warbosses which turn into the Astart equivilant based on just sheer muscle mass and brutality. Unfortuantly they do not reproduce often so they poose little threat.
Nids have Tyrant Guards, and Warriors which breed like crazy and have the strength of 2 Astartes in one. It remains to be deteremined if they pose a threat to Astartes, but it has been well documented they are a challenged to kill.
Guard keeps their assasins and Ogryns in their back pockets while various type of Skitarii and Elites prowle the Inquisitorial ranks. Few of these can even compare to an Astarte, yet their arsenal is certainly none to gawk at.
Chaos....well their alreayd Astarte :p the Daemonics dont' really need to contend, they can just think up their new superhumans; it's the reason the Astarte exiast quite honestly.
Necrons have the Lych Gaurds and Traich Preatorians. Especially with the Lych Guard their CQC abilities are second to none. I would love to see a 10 vs 10 with Astartes and these bad boys just to see whow ould win out.
Eldar don't really have any heavy hitters like Astarte but often employee Autarchs and Warlocks to combat these Troop choices. Warlocks especially have good CQC abiltiies though I'm unsure, both in TT and Lore, if they have the psychical ability and armor to hang in their with Astarte.
Grotesques are the only real unit with enough firepower and armor to go toe-to-toe with Astarte. The style of warfare favored by the Dark Eldar do not allow for heavy units in thick power armor.
In conclusion each race has it's own version of heavy troops, but only Humanity can lay claim to Legions of "Super Soldiers," in terms of size. Sadly though as GW evolves the game Astartes are becoming more basic line troops, and power armor is sadly finding it's weakness as new strategies and weapons become avalaiable.