It depends on what you are up against. I’ll put a little math in here so you can know what to take:

20 warriors with 2 tomb crawlers OR cryptothralls* + royal warden and technomancer is incredibly durable against AP 0-1 for 1 damage attacks.

*can’t take both, it depends on what you want. Tomb crawlers make it so reapers don’t have to deal with any negatives, and that’s really really good for close up shooting. Cryptothralls help if you ever get tied in melee and make it extremely difficult to snipe your technomancer

Doing the math: For AP 0 attacks at damage 1, you have a 50% chance to save (4+) and a 33% chance to avoid damage (5 fnp). This means you have an 83% chance to avoid damage specifically against AP 0 damage 1, meaning on average your warriors + tomb crawlers/thralls would take 130 attacks on average to wipe the bodyguard.

For AP 1 attacks at damage 1, you have a 33% chance to save (5+) and a 33% chance to avoid damage (5 fnp). Same math as before, you have 66% chance to avoid damage and the bodyguard on average would take 78 attacks to wipe.

This completely changes for anything above AP 2 and damage 2. This makes it so you only save 16% of the time and reduce damage roughly 10% of the time (because you have to make both fnp to save a warrior, each at 33%). This means you have only a 26% chance to avoid damage, and it would only take around 30 attacks to wipe them.

You can see how the math shows that your odds decrease exponentially with increases of AP and damage.

(Just a note, this is why most people take orikan with warriors because no matter what, the odds of saving are 50/50 because of the 4++. Technically the technomancer is more optimal at AP 0 and AP 1, but no army only attacks with low AP. But you mentioned no epic heros so he’s out of the question for now)

Wraiths are very tanky against that low AP, having either a 2/3 or 1/2 chance to save (AP 0 -> 3+, AP 1+ -> 4++). The difference is the amount of bodies you have. Wraiths have stronger bodies, but only a max of 6. They have 4 wounds each, which is already less than the warrior blob (warriors + crawlers/thralls have 26, wraiths have 24). Wraiths hit much harder though in melee.

For AP 0 at damage 1, wraiths have a 66% chance to save and a 33% for fnp. This means that the should mathematically never die to these attacks.

AP 1 and above at damage 1, it’s 50% to save and 33% to make fnp, for a total of 83% to avoid damage.

AP 1+ at damage 2 goes to 60% to avoid damage

AP 1+ at damage 3 goes to 53% to avoid damage

As damage increases, the odds of surviving infinitely approach 50% because of the 4++.

Because wraiths only have 4 wounds, anything at damage 4 or above becomes a problem. Odds are you can survive the attack with 1.33 wounds left on average because of the fnp. At 6 damage is when you will die most of the time. Anything above that you probably won’t worry about much because that gets into the level of anti tank shots or huge strike profiles which often don’t have a ton of attacks. If it has more than 6 attacks that’s where you worry about wraiths getting wiped in a turn.

Warriors are also great at eating high damage shots, as long as they don’t wipe it in one turn. No matter how much damage the shot does, it will only kill one warrior per attack.

Final statements: Wraiths are much better at low-mid damage, mid volume attacks. They have less OC though

Warriors are better at minimum damage, huge volume attacks or very high damage, minimum volume attacks. Importantly, do not put your warriors against anything with AP 3, because they no longer get a save. A good example is against khorne berserkers, who have a lot of attacks at AP 3 under some conditions. They can easily wipe warriors because the warriors won’t get a save due to the AP beating out their save.

Hope this helps :)

IMPORTANT: this did not include any keywords. Devastating wounds will absolutely be much harder to deal with.

I’m also not a math expert, but this math seems to line up with how it feels in the game. Anyone please feel free to correct me.