W/c of the two skills does more damage?

Net damage increases the amount your critical hits hurt/damage only and does not effect everytime you simply hit a player for damage without critting them in the process. So if you are crit and crit dmg geared/built/specced then Net dmg is more effective. If you are hit specced OR enjoy healing as a priest then ultra damage is more important for those gamer types because repetitive hit dmg adds up fast and it makes your heal spell stronger/more effective.