PvP: Divine, Arcane, Starfall
The number of builds using a sort of "holy" or "divine" spell type are too powerful. These spell types lack a way to resist; you can get basic spell damage reduction, but never be able to stack holy. On this basis, I believe that Divine should not be one of the highest damaging spell types, and instead should be a sort of "armor piercing" for magic. If I stack a bunch of shadow resist, for example, now Holy/Divine would be better than dealing shadow damage to me.
As it stands now, these Holy/Divine builds can have pretty damaging attacks and there is nothing you can do about it. I just think it's a bit oppressive.
Arcane we have a little bit of the same issues. Starfall is a huge problem; this thing is hitting for 1600 crits every second IN AN AOE. Again, you cannot stack Arcane resistance in the way that you could stack Shadow or Fire. I'm a resto druid and I can't throw a silence without leaving form and using 2 GCDs, and I could only do that every 45s with the investment. That, and starfall cannot be interrupted; it simply deals ridiculous, nearly unmitigable oppressive AoE damage.
The Starfall/Arcane builds are a huge pain point in BGs right now. Whoever has the most arcane boomkins seem to win. It makes it very unfun if 3/10 players are the same boomkin arcane build in every bg.
As it stands, Starfall probably deals more than double the damage of what would be considered appropriate AoE damage.
I don't know if I'm alone in this, but it does feel kind of awful.