FvS get higher spell points:
A Favored Soul also gets bonus spell points from his Charisma or Wisdom modifier (higher ability applies). Favored Soul also gain double the spell points from items
Clerics gain additional spell points when they increase level or by having high wisdom
Primary stat for hit and damage with favored weapons (helps with tank builds)
Grace of Battle
Knowledge of Battle
Free HP or SP like the Animal Domain or Magic Domain (if you choose HP, you get more HP and SP than a Cleric, if you choose SP, you get a lot more SP than a cleric and the same HP).
Stout of Heart
Purity of Heart
Clerics can get more Necro DCs by giving up the the FvS HP but if you want a instant kills, you won't even get close to a Wizard. R10 level DCs are too high for Clerics ATM. I know I have a uber completionest that has tried, and the best he could do is about 10 DCs behind a Wizard (still 3 higher than a FvS but with less SP).
Stacking Energy Absorptions
Free Leap of Faith comes in pretty handy
Damage Reduction