Favorite moment? There are way too many to count.
The Belgariad - When the Baron of Vo Mandor launches into his flowery insults, most notably "... Prey thee, did thy mother perhaps dally with a randy goat?"
The Mallorean - so many, the scene where Garion gets upset with Zakath about being held as prisoner, he draws Irongrips sword and unleashes the power of the Orb on the door, intending to unhinge it, but rather destroys the door, door frame, wall, and wall across the hall.
The Elenium - As so many have said any Scene with Kalten, Ulath, or Kurik. And when Bevier loops off the head of the Captain of the Church Soldiers outside the Basillca with a 'nonchellant' wave of his hand holding his Lochaber Axe. Too cool!
The Tamuli - As so many have said any Scene with Kalten, Ultah, or Khalad.
I first started reading the Belgariad 18 years ago. Now I am reading them to my children as bedtime stories, all be it censored for content.