3D6 and pick the highest on run moves*
Reroll CC wounds
+1 pain token
I'm going to calculate the average number of kills on the charge for a single wych and for one with each type of wych weapon. (the 2 good ones, anyways) I will then use the numbers to determine which setup I can expect to perform the best.
|v MEq||v GEq||v 5's@|
@ - 5's is a statline I usually run math against in these sorts of comparisons. Generally speaking, it is a unit with 5's across its statline and a 2+ (5 chances to save) hence 5's. It doesn't necessarily represent a specific unit, but it is something that is supposed to be a very tough enemy that is generally the most trouble I expect to run into with generalist troops. It is supposed to show a worst-case scenario type of encounter. Obviously plenty of things have T6 or higher, but if I'm charging a 'fex it really won't matter. Either the wyches are my last unit, the 'fex is his last unit, or it's a desperate bottom-of-the-9th move that the entire game rests upon; in any case, it's not something I'm going to be planning for when I choose which drugs I want.
So now that we have our killing values, let's see what loadout will be the best.
(I'm assuming 8 CCW wyches with 1 special weapon, the 10th is the Haemonculus, so each value will be 8*wych + RF or HG)
|v MEq||v GEq||v 5's|
|8 + 1Razorflail||+1S||2.562||10.86||0.594|
|8 + 1Hydra Gaunt||+1S||2.458||10.93||0.592|
Well there we have it. Generally speaking, the razorflail comes out on top. On average, that is. The problem (and strength) with the gauntlets is they are random. Attacks become 1+D6, which can be great if you roll all 4+, but awful if you roll 3-. As Brent says, "consistent is competitive". What this math shows is that, fortunately, we can take the more reliable option and know that it is both more consistent and better on average. We can have that reliability without gimping ourselves. What will end up happening if you take the gauntlets is every 3-strong squad of guardsmen you face will roll 6's, and every group of TWC will roll 1's. That's just how it goes, so the dependability will be very nice to have.
So I think I will take a razorflail in my wych squad and prioritize drugs as follows:
1(0.305) - Reroll wounds
2(0.25) - +1S
3(0.194) - +1A
4(0.138) - +1WS
5(0.111) - D3 run/pain token depending on the situation
Even though the flails come with reroll to wounds and thus the drugs are wasted on them, the effects they have on the rest of the squad are enough to make it the best option.
The paren values represent the chance that I will get that outcome. Yes, in 2 dice each value has the same percent chance of being rolled (assuming perfectly fair dice, lawl) but if I roll a 2 and a 1, the 2 doesn't count because I'll pick the 1 every time. For example, there are only 4 rolls in 36 possible that will make me choose my least favorable option: (1,1)(1,6)(6,1)(6,6). Pretty favorable odds, if you ask me.
* - If I can help it, I don't plan to take either a 1 or a 6 on the roll for this. D3 on a run move doesn't seem especially useful since I don't expect them to do much running**, and the free pain token is nice but they already get 1 free from the haemonculus and with I6 already, furious charge isn't going to be as useful as a flat +1S.
** - You know, because AV10 open-topped skimmers are so durable...