Knights in Combat I've done a comparison of just over 500pts worth of Knight Errants with two other similar priced formations.
The formation were chosen for specific reasons:
1) None are Fearless or have ATSNKF built into their price,
2) They all have similar armour (probably a fair comparison; Reinforced; 4+RA is better in most circumstances than Knight 4+/5+, but worse vs the TK CC weapons that are on the chart. In addition it takes 2 wounds to remove a knight from the fight, compared to 1 per Tank/Terminator)
3) Chaos Terminators are a gold standard for durable Close Combat, and Minervans for durable Fire Fight assault.
Each unit has a row for its CC damage output and a separate one for FF output. The Knights have additional rows to show how it performs with extra attacks when charging.
For example, on the Charge 5 Knight Errants will do an average of 5 CC hits, 0 CC Macro Hits and CC 2.5 Titan Killing hits, with a bonus 1.6 FireFight first strike attacks
*Note: AFAIK the unit can combine the attacks; get the Firefight EA+1 First strike when charging and do the rest of the attacks as Close Combat
Excellent is marked in red, Very Good is marked in orange
Amongst other things, what this shows is that Knights are excellent in Close Combat whether charged or charging. The difference is much smaller than I had anticipated after seeing some of the battle reports; is it possible it feels a bigger difference than it is?
That's not meant to under-rate the impact of the shock lances; any First Strike ability is significant, and First Strike FF far more than most. What I didn't find was that Knights are in any way bad when charged, merely that they aren't
as good.
As you can see, the Errants are very good in CC while Terminators are Excellent and Exterminators Awful.
Errants are also excellent in FF (because their basic FF is macro), as are Exterminators, and Terminators are mediocre
This is the same table with with the amount of Marines (or any 4+ armour) and Terminators (or any 4+RA) the units can expect to kill.
As you can see, when it comes to inflicting casualties the Terminators are really poor in firefight, and the Exterminators even worse in Close Combat.
The Knights, with their combination of EA First Strike (when charging), Titan killing close combat and Macro fire fight are between very good and excellent in all of the above cases, whether charging or not.
Chaos Terminators outperform them in close combat, but are far behind in FF. In fact, Knights are less than a fifth of a kill behind Terminators when it comes to killing Reinforced Armour units on the charge, and since the Knight formation is fractionally less expensive they're pretty even.
If they charge, 5 Errants outperform 10 Executioners in Firefight, and even if they don't charge they score very similar results, and obviously are leagues ahead in CC. They actually make the fire-fight specialist executioner tanks I've used at some tournaments look very average, which frankly was a surprise to me.
It's also worth noting that the Errants have more bodies in the fight (10) than the terminators (8) and are the cheapest of the 3 formations.
Anything that looks decent compared to Terminators in close combat AND looks good compared to Minervan Executioners in Fire Fight has to be a pretty versatile killing machine.