I've been using HOTW all week. But in order of bosses:
1 - NV
2 - NV/HOTW
3 - HOTW
4 - HOTW
5 - NV/HOTW
6 - HOTW
7 - HOTW
8 - HOTW
9 - HOTW
10 - NV/HOTW
11 - NV/HOTW
12 - HOTW

NV - damage amp is very good, or the passive healing is nice
HOTW - more raw stats (spell power) seems to be a better choice, healing passively isnt needed
NV/HOTW - pick your poison