I have been playing Menoth for a few months now, so I am pretty much an authority on the True Law. I thought that I would lay out my thoughts and experiences with Mennites thus far.
I have only played three Menoth Warcasters so far. I looked through the book and decided which ones seemed to fit my playstyle the best.
Harbinger of Menoth
The floating chick is probably my favorite Mennite. Purification is amazing, her feat locks down infantry for a turn, and who doesn't like 10 focus to hand out. This is basically a gunline army. I have gone through four other units with this army, and finally settled on Zealots. I like the Exemplar Errants, but they aren't as effective without Defenders Ward.
Right now, my Harbinger list looks like this:
Vessel of Judgement
Zealots (Max) + UA
Vassal x 2
Mechanic x 2
Prime Kreoss is a dangerous dude. An evil feat, purification, defenders ward, and lamentation round out a great spell list. I run him as a gunline as well, and keep the pop and drop in mind every turn. I had more infantry in this army, but I found that I lost most of it before they got to the fight. I added a couple of light jacks and haven't regretted it.
This newest version of my Kreoss army has only been played twice, but it has won both times.
Errants + UA
Exemplar Errant Seneschal
Vassal x 2
When I was choosing casters for Menoth, this guy caught my eye, but much of the talk on the forums said he wasn't very good. Luckily I didn't listen to them. True Path defines Vindictus for me. Buffing the speed of our toughest infantry is unique to him, and a great advantage. Not sure what my record with this list is, but I think I am 3-1 with it.
Here is my current Vindictus list:
Zealots (Max) + UA
Reckoner and Vanquisher
If you can't tell, i really like this combination. I like the utility they provide together. Put the Vanquisher across from the enemies infantry, and use the reckoners long range to threaten important targets. After the battle closes, these two can hold their own in melee too. I was running double reckoners with Harby and Vindictus, and double vanquishers with Kreoss, but I started to pair them up instead. The great thing about Menoth is they have several great jacks that all cost 8 points, so you can experiment without switching your lists up too much.
Vassal of Menoth
I love these guys. I will share a mistake that I occasionally make with you. Always check for an Enliven opportunity before you look to make an Ancillary Attack. Keeping a warjack alive is usually more important killing an extra trooper or putting a few more damage on a beast that will still be alive next turn.
Zealots and the Monolith Bearer
I am pro meat shield in this game. I never hit the table without one. These guys do it well. On turn 2 (or whatever turn you want) they are immune to damage from every source except feats. On turn 3, they are lobbing pow 14 bombs all over the place. It is easy to look past them for flashier units, but for 8 points, you can't go wrong.
I have only fielded him in the last 2 games that I have played. Before that, I read Inaccurate and turned the page. Don't fall into this trap. Inaccurate brings him down to RAT 1. With the choir, aiming, and Flare from the Reckoner, he is back up to Rat 7!
4 points! We all love sprays, especially when the choir buffs them. Pow 14s are nothing to sneeze at.
I think Menoth is the most balanced force in the game. They have a great combination of melee, ranged, and control available to them. I have played several factions heavily, but I think Menoth is where I am going to stay.