EDIT (1/16/2021): Reworked this analysis due to recent attachment re-balance. Previously these tests assumed Bone Plate attachment. I have now removed the BP and am testing with no attachment. I've also reformatted the post for easier reading, and I've changed the metric returned to avg. number of hits to die instead of just adding the total number of hits taken because that old metric was kind of meaningless except for comparison sake. Avg. hits until death is more understandable. Conclusions have remained the same.

EDIT (8/13/20): I added 4 more enemies to the test group in the calculator and a few other updates. I've rerun the numbers. Blazing Deserts also introduced new armor, notably the Assassin set with 140 (Assassin Metal Mask) and 120 (Assassin Robes). The 140/120 set is a perfect -15 for Nimble, and clearly the best Nimble line. It is held back by the rarity/difficulty of obtaining the armor. I've updated the OP with the new calculations and put in an Assassin line for reference. Information in the comments may contain outdated information.

I said I was going to do something like this awhile back, and here it is. Let's take a look at how a few 40% Nimble options do against a gauntlet of 35 enemies and for fun let's also check how Gifted and Brow do. TLDR conclusions at the end if you don't care about the methodology and numbers.

How I'm going to score each test is the average mean number of hits they survive against all 35 enemies (the test will give 35 means, then I mean the means for the score). The enemies are drawn from all factions and most weapon types are represented. However, there is a bias toward more dangerous enemies (ie: 4 Chosen tests, no Weidergangers). Enemy perks and weapon logic is factored.

The Nimble lines being tested are as follows:

• 120/95 (Sallet + Leather Lamellar)
  
• 190/65 (Barbute + Gambeson)
  
• 40/160 (Necro Hat + Noble Mail)
  
• 140/120 (Assassin Mask + Assassin Robes)

• Nimble, Colossus, and no attachment are assumed.
  
• Enemies will have their respective perks/weapon skills in play.
  
• 100% hit chance (except in the specific Chosen test at the bottom)

• This is an obvious oversimplification. I still think the data is useful.
  
• I've limited testing to 40% lines, because the way the scoring works tends to make it difficult to compare other lines without a lot of skepticism. For example, Noble Mail lines survive more hits against Boondock Bows which skews results in their favor, even though they may die faster against Chosen.
  
• The score doesn't tell the full story of course. Just because a line scores the highest in the enemy gauntlet, doesn't necessarily mean it is always to best choice.
  
• Gifted test is just +5 hp (Colossus assumed). The calculator does not factor hit chances.
  
• Attachments are not factored, and may have differing value depending on the line used (ie Bone Plates would offer better return on Nimble lines that are biased toward more head armor).
  
• The calculations are obviously biased to the 35 enemies I tested against and the weapons I have given them. I can't test everything.

Recall that defender has Nimble, Colossus, and no attachment. Score is the average mean number of hits to die against the 35 test enemies. Gifted is just +5 HP here.


Here is a more granular example of a defender with 25 melee defense + Underdog vs a Chosen 2H Mace Cudgel + Crippling + Executioner. Hit chance is factored into this one, so without Gifted there will be a 50% hit chance and down to 47% with. Defender still has Nimble/Colossus/No attachment. Defender has 100 HP before Gifted (Colossus assumed). Scores are the number of expected swings (not hits) taken until death.

• The new (as of BD) Assassin set is clearly superior to our old options.
  
• The helmet favored line (190/65) works better the higher your HP, as it means you are more likely to survive long enough to get hit in the head multiple times. Not shown here, but you can drop to a Necro Shirt (60) and add Bone Plates while staying at 15 Fat cost.
  
• The 40/160 Brow line consistently scores the highest, but not by much, and is only about equal to the Assassin set when it doesn't have Brow.
  
• Switching to 40/160 Brow line from the no-perk non-Assassin lines is roughly worth + .64-.67 hits taken. Gifted 5 hp is roughly worth .18-.23 hits taken on those lines. We can loosely say that Brow is worth about 15 hp, (or 3 level ups in hp), but maybe that is too much extrapolation.
  
• Brow gains are slightly lower when used on a regular line instead of the lopsided Noble Mail line.
  
• While I did not display Injury numbers, the Brow lines had the best scores for Injury avoidance. However, this doesn't factor in the +3 Gifted defense.
  
• It is very difficult to put concrete value on the 3 Gifted defense, but the impact of the +3 defense will be greater the higher the unit's defense stat is due to the nature of increasing returns from high defense. There's also the + Skill that Gifted offers.
  
• The Assassin set is the new go-to Nimble option should you be able to acquire them.

Thanks for reading.

To see an analysis with attachments, please refer to the following link:
─ Nimble With Attachments Calculations