Sunfire Burst compared to Arc Lightning is a pretty nice match up actually. They both deal an average of 3 damage to an unarmored target, with Sunfire Burst doing better than Arc Lightning against armor. Sunfire Burst also has a better Daze chance and +2 vs non-living targets, but lacks the chance to Stun. They're pretty even.
When you throw in the Priest's Malakai's Fire ability, bumping the average damage of Sunfire Burst up to 5.5 against unarmored targets for an extra one mana investment, then it's no contest at all.
Pillar of Light does seem to lag behind though. It is 1 less damage on average and lacks the unavoidable trait and all it really has going for it is an increased Daze chance and increased range. Not really impressive.
I would personally be very happy just to see Sunfire Burst be printed, but I think I would also like to see a level 2 non-zone light attack spell. Something that is supposed to be the equivalent of a Lightning Bolt or Fireball would be cool.
Maybe something like:
8 Mana, Quickcast, 0-2 range, targets Creature or Conjuration
4 attack dice, 5-6 Daze, 7+ Daze and Burn, Ethereal, +2 vs non-living