I like the Vans as well, however, the low strength+spear combo (damage only 14!) is hurting them and without some bless effects I think there are several more priceworthy options.
My absolute favorite cavalry for the moment (although it can hardly be called a knight unit) is Pangeas Centaur Warrior (CW). These are the stats:
code:
hp 20
prot 11
mor 12
MR 13
str 13
att 10
def 16
mov 3/29
gold/res 40/11
These stats are quite good in themselves, (except for prot and attack), however, what makes CWs shine are their wonderful 'add-ons'
1. Berserk +3. This is a Nature 8 blessing for free! Very nice increase to protection, attack and damage. Defense will decrease to 13, which however still is quite decent.
2. Recuperation. Due to the low prot the CWs will get hurt a lot, however they have a good chance of surviving thanks to the 20 hp. I see very few afflictions among my squads with 2 or 3 stars veterans.
3. Sneaky. Only Vanheim has better (but more expensive) sneaking troops
4. Forest survival. Most importantly, this makes it possible to take full advantage of the strategic move of 3.
5. Hoof damage = Strength. Normal cavalry have a somewhat useless Hoof attack with damage 10 (strength not added). Pangeans Hoof damage is 0 with strength added. For CWs that means 13 normal, then 16! when they go berserk.
Since I use CWs as the core of my Pangean armies, I can easily afford to take sloth 2, giving me points to spend elsewhere.
Buffs are an issue by itself, but IMO a Pan casting Summon Earth Power/Legions of Steel/Strength of Giants on a squad of CWs with Hold and Attack orders will create a truly awesome force, capable of taking on any standard troops. And then of course there is Mass Protection. 
/Patrik