Alright i meant to just find a reply for you but then went down a rabbit hole. I'm gonna post this as its own thing but you started it so I figured I'd reply to you as well ;P

Well I just made a ♥♥♥♥♥♥♥ spreadsheet cuz I was sick of questioning this myself. I'm not using any combat overhaul mods so YMMV. I'm assuming normal quality for all pieces. And I'm playing through on a melee only colony so I didn't look at anything ranged related. Sorry y'all but I spent too much time on this as it is lol.

So tons of armors etc. are just reskins of other stuff. Like pants, Briaes, Trousers are all the same stats. And for leather materials the best is Rox leather, Gryphon Leather, or Daer Leather. Notably, Lindwurm has unique options to make out of it and its leather is just as defensive but not as insulatory, so I don't recommend Lindwurm for general leather usage. ROX WOOL IS NOT AS GOOD AS ITS LEATHER. Don't get these mixed up =3. But all 3 of those leathers outperform thrumbofur. Also I'm assuming Devilstrand is the best fabric because I don't believe hyperweave is available in this pack? And for metal obviously plasteel is the best.

For boots, its 49.9% defense on plasteel plate boots with a -0.1 move speed vs 39.6% defense with a 0.05 INCREASE to speed. For raw defense go plasteel, but to offset move penalties, the leather could be better for you.

For gloves, same thing. 49.9% defense on plasteel with a 10% work speed reduction vs a 39.6% defense on leather with a 5% speed increase.

For shields which are in the "On Top" slot so I think everyone can always use one? The heater is best defense at 75% but gives -5 dodge AND -2 melee hit chance. Kite shields are only 39.6% defense but no melee hit chance reduction. But still the -5 to melee dodge. I'm not sure whether the dodge is better or the defense, but I think it would be the defense.

For pants, it's just a clear win for leather Padded Chauses at 66% (Yay! A simple one!!!) the plasteel was only 52.5% and there's no negative stats for any of them.
For the skin layer of your legs you can do leather trousers, briaes, pants, whatever its all the same. But leather is the best.

For helmet there's different options. The best defense is with the Lindwurm Scale Helmet though. 105% defense, but a -2 to melee hit chance. BUT it also gives a 15% pain shock threshold so you can keep going 15% more into pain before going down. This CAN be good, because you stay up swinging, but it can be bad because you will gain more injuries before going down making your pawns more likely to die. Lastly this piece also prevents lindwurm acid so if you're gonna go after more of them, this is the play. Second best is the Plasteel Armet with 79.9% but no pain threshold increase. There were no comparable leather options I found. They all only covered the head and ears, not the eyes etc.

NOW FOR THE UPPER BODY OH GOD HELP ME.

Skin layer is easy. Leather Button Up Shirt / Formal shirt give 44%, and Devilstrand Gambeson / Padded Surcoat give 42%. They're super similar. Just wear what you'd like tbh. I like gambesons so that's what I'm doing. Also the devilstrand is easier to get than the high quality monster leathers.

Okay so for looking at an outer-middle mix you've got heavy plate, Plate, or Heavy Leather. In terms of raw defense, Heavy Leather takes it by a mile. 187% defense is like 100% more than the other 2 options. AND it has better dodge than heavy plate, and more move than it. And the Plate doesn't give a dodge decrease, but like 100% less armor. Overall, I think heavy leather is just best in show for a super heavy Outer+Middle. THIS ALSO COVERS YOUR LEGS, so no Leather Chausses needed if you go this route.

Now Looking at the best Outer only for upper body, there's a lot of options. For no movement penalty, Light Lamellar gives the best defense at 114%, but doesn't cover the arms so I don't recommend it. Dusters aren't great in comparrison at 66% defense, but it covers pretty much the whole body. If you want no movement penalty, It's between those two. If you prioritize your vitals go lamellar, if you prioritize all injuries then duster? Overall these are still pretty lackluster vs the options that do reduce speed. So I'd rather go with those.

For outers that do reduce move speed we're got tons of different plates etc. but one stands out. The heavy hitter for this slot are the Lindwurm Armor made with Plasteel, at 88.5% defense for full body. Only a 0.6 move penalty. This thing's good. AND it prevents lindwurm acid damage. If you're gonna fight more of these things, then why not wear it. But surprisingly the best defense comes with the Heavy Leather Armor. This is the best move speed vs all except the zweihander cuirass and breastplate but those don't cover the whole body, and defense is within a few percent.

But if picking an outer AND middle combo, we need to find the best middle to go with your outer. Now that would be great if there wasn't only one option in the Hauberk. It gives an underwhelming 63% armor and -0.4 move. That's it. That's your middle option. I HOPE I missed one so we have some better choices but I couldn't find any. Adding the 63% armor (I'm sure the computation is harder than that but I'm just doing me slow brain maths) to our best outer only of Lindwurm scale, which gives 88.5% we total up to... 140%ish. Wait that's close to the heavy leather Outer+Middle option!... well.... kinda. About 40% shy still. But now the bad news. We also need to add the speed hindrance. We have -0.4 from the Hauberk and -0.6 for the lindwurm scale... for total of -1.0. We are now moving SLOWER than if we just wore the combo armor. This doesn't feel worth it at all anymore and I'm scrapping this option =3.

Comparing the Outer+Middle combined vs each individually, we end up with better defense, AND better movement speed for the Heavy Leather Armor. It can also come from multiple monster sources instead of just Lindwurm. The clear winner for me is going to be the combo.

TL:DR So let's put all this together and build a pawn!

THE BUILD: Outer/Middle combined heavy leather melee warrior.
Head - Lindwurm Scale Helmet (Heavy Barbute until you can make one)
Outer+middle upper and legs - Heavy Leather
Skin upper body - Gambeson (Within a few percent defense, and way cheaper than leather, also feels more medieval than a button up or formal shirt)
Skin lower body - Briaes (All are equivalent)
Boots - Leather boots (difference of about 10% def for speed vs plate, I pick speed)
Hands - Leather gloves (difference of about 10% work speed vs plate, I pick work speed)
On Top - Heater Shield

Overall move penalty = 0.75
Overall work speed bonus = 5%
Overall dodge penalty = 13
Melee hit chance penalty = 4 (2 if you don't have lindwurm scale helm yet)
Pain tolerance threshold = 15% increase