Just going back over the HH book series, and they keep hammering on about people with horns and stuff still having gaps in their armour (DA crusader ships on rim iirc) and that the newer stuff (as in just before heresy breaches) is the best stuff). so highly sort after its not spread out much yet.And after thats when things start falling apart.
Since mechanicum split and yada yada war of attrition etc..nobody has any real science.. but whats the timeline with rediscovering STC machines..
When was the bestest time to go to Q for your stuff?

The beginning as far as i can see because chaos marines are just as good as marines of today as it looks like a "if it aint broke dont fix it" they just redesigned it as time went on but never improved on it or made easier to wear....also (just guessing here) it seems that the crusade armor was easier to adapt and customise to each legions needs

Depends on your definition of best.

The most recent, MkVIII "eagle" armour is the latest update on the MkVI which was in the process of being rolled out at the Heresy. Terminator arour is the logical extension of "power" armour, but is fairly restrictiv to the user. During the heresy, most marines would have been in MkIV, V, or VI. How good the armour is depends on the requirements of the 'plot'.

http://warhammer40k.wikia.com/wiki/Power_Armour

Dammit - MkVIII isn't eagle - my memory is failing me.

Mark IV Maximus armour is widely considered the best armour. It's design was for quality and implemented the best of the best of Imperial technologies. Where as the armour that followed were a compromise of supply and demand as well as understanding. It's arguable whether the newer marks have managed to get back the same level of quality and function of the older suits in the many years after the Heresy. I'd like the think they have, but who knows for sure? In Deathwatch the RPG the newer armours have a much better protection and gizmo's but have no were near the same level or respect or reverence that the older marks have and seems that the older the armour the better (for moral at least).

Ljundhammer wrote:How good the armour is depends on the requirements of the 'plot'.

*waves goodbye to everyone*

Ljundhammer wrote:Dammit - MkVIII isn't eagle - my memory is failing me.

That's actually the only Mk I can name with 100% certainty

Agree with Nikki, from a fluff point of view the Mk IV seems to be the best. The Mk V stuff was supposed to have been massed produced to replace the losses of the Heresy and was of a lower quality. The Mk VI was an improvement over the Mk V but if it was any better than the Mk IV is never really discussed.