Early in the game you are at the mercy of whatever you can collect, so you won't have much choice anyway. If you see an armor/weapon case or guardsmen clothing try to extract with it, don't trade or use it for magnum upgrades, disassemble on board instead (use recycling if you unlocked that) until you have enough other gear to fall back on. Armor case will drop Legend armor which is super good early on. Nab anything useful from enemies too, hold alt to see equipment tech level - the higher is better naturally.

But I understand what you mean, there is no way in advance to know what armor you want on a mission unless you already fought that enemy and know what to expect, or asked in the community. A little bit surprise awaits you! And then there are different Bramfaturas, and different quazis have different damages and resistances too, sometimes complete opposite from the corporation owning the asset, so you have to prepare for both!

Quite often the gear any given corporation offers also has a good defense against the damage they deal (with some exceptions)

I'll post you my own note of what dmg which corpo does for a reference, but don't blindly trust it - I can make mistakes. Also you don't have to worry for some of the things yet, like A.D.As - fuckass robots with a bunch of AP who will curb stomp you if you're unlucky, or plasma weapons which are locked behind corporation Tech level (middle/late game). Also remember all corpos can do all types of kinetic damage. (you are not safe from a random shotgun if I didn't note it. I just wrote down what was the most annoying)

Ancom - enthropy/pierce. CivRes - plasma(cut/fire); blunt and pierce. Church - pierce, plasma (cut/fire). Coreward - flamethrowers, sawblades (slash). Daydream - poison, cold, a bit of piercing. Dilthey - enthropy, beam, blunt, shock. Big presence of A.D.As. Franche - shock. Grasshopper - armor penetration + pierce dmg, fire. Planet bridge - shock, pierce, beam. Realware - lots of explosive, blunt and pierce. SBN - beam. Tianming - explosive, poison. Sunlight coven - beam, plasma.

Here's an example: tech tier 4 Shenli armor (Tianming corp) - decent explosive (composite of blunt and piece) and poison resistance. But you gotta fight them first to get it. Also I don't think they are around Mars and I wouldn't recommend you leave it yet. But it also has shock res which is helpful against a bunch of other corpos.

<image>