[Alneyan]

Armour is paramount: Stealth and Scattering Armour give you a huge bonus to defence, and those are definitively worth it.

Now as for Armour vs Shields... I'd rather not engage in that debate. Let's just say shields are more expensive, Shield Depleters do a lot of damage against them (and are otherwise worthless), but shields give more hitpoints per kt. There are other differences, but I would need to write a paper on the matter, so I won't do it right now.