[These were my thoughts after the Kings of April tournament, posted on the KoW Fanatics FB group].
The Shield Wall is surprisingly resilient. I thought a Def 4 unit would not be tough enough to be a proper anvil, but it can take at least 1 punch from all but the hardest hitters so if you have stuff ready to flank it's job done.
The Arquebusier Horde (with brew of keen eye) is awesome, slaps 5-8 wounds on pretty much any target, but if the enemy has fast individuals will only get 1-2 shots off before disruption. I still love it.
The Knights are great, benefit greatly from having the pathfinder & haste potions. Classic hammer units.
The Foot Guard Regiment w 2 handers is another good hammer. Harder to get into position than the knights, it hits nearly as hard and is much cheaper.
Mounted Scouts are fantastic. I usually run two troops of these. Able to screen for my knights, hold objectives, can take out war machines, and can force nerve checks with 1-2 wounds with an 18" range. Love them a lot.
The Steam Tank (beast of War) is great in extended fights, but it is a bit of a bullet magnet. Hard to cover, and people love to shoot at it. In 2 out of the 4 games on the weekend it was shot off the table before I got to move it. But in the other 2 games it made a major impact.
My mounted standard bearer with the heal charm is another really useful unit, significantly increasing survivability.
My war machines are iffy. One game my mortar didn't land a single hit, another game it landed 4. I'm considering dropping them for 2k games, but they are really useful for tagging high def flyers so still on the fence. In 2500pt games I often run 3 of them.
Wizards with Lightning bolt and bane chant are great force multipliers.
The Captain is a tough one. His tactical redeploy can be awesome, but not reliably. I usually send him off to hunt shooter hordes or war machines, so his inspiring usually only covers himself. Considering swapping him for a mounted hero next time. But it is nice having a very points dense unit in scenarios like Dominate.
The General on a Winged beast is useful too. Not as much of a powerhouse as a dragon, but for 190 points he's a lot cheaper. For a 2k game I wouldn't bother putting ensorcelled armour or regen on him. I usually have him work with my 2 knights and scouts on one flank.